Now Another Problem.....

[GRSHOPR]

So I've got the fuel pump in, everything connected, even the battery, and I tried to turn it over, but nothing. Any ideas why it won't turn over?? This is a 91 JDM TT motor in a 94 base 3000GT, along with a JDM ECU and harness. Thanks or the help.

[Austin@STM]

Battery dead?
Positive from battery, and trigger wire both hooked up to starter?
Engine not grounded?
Blown fuse?
Bad starter?

Does it do anything, buzz or click at least? Grab a mulitmeter and start testing.

[GRSHOPR]

Battery definitely not dead, I'll double-check the starter, engine is grounded. Which fuse? And it's the same starter I was using before. No buzzing, but the fuel pump clicks.

[stealthee]

Lets make sure your terminology isnt wrong. Is the engine cranking? If it is then the engine is turning over, its just not firing.

[GRSHOPR]

OK, so I checked the starter, it's definitely got current to it. I checked the relay in the fuse box under the hood, and no power?? There is also every 10 seconds or so the sound of a motor turning in the hatch lid. Any idea what that is?? I also do not have headlights. Did I somehow bypass part of the fuse box??

[GRSHOPR]

Lets make sure your terminology isnt wrong. Is the engine cranking? If it is then the engine is turning over, its just not firing.

Nope, it's not doing either. And there is definitely power to the starter, but not the relay?? And a few other issues that I wrote about in the next post up.

[Austin@STM]

Does the smaller wire on the starter have voltage when you turn the key to start?

[GRSHOPR]

Does the smaller wire on the starter have voltage when you turn the key to start?

The clip?

[CoreyB]

OK, so I checked the starter, it's definitely got current to it. I checked the relay in the fuse box under the hood, and no power?? There is also every 10 seconds or so the sound of a motor turning in the hatch lid. Any idea what that is?? I also do not have headlights. Did I somehow bypass part of the fuse box??
The motor in the rear is the power antenna. If you want you can cross the big wire on the starter to the small wire. It should turn over then. Then its just a matter of figuring out why you have no power to the smaller wire.

[GRSHOPR]

The motor in the rear is the power antenna. If you want you can cross the big wire on the starter to the small wire. It should turn over then. Then its just a matter of figuring out why you have no power to the smaller wire.

It can't be the power antenna. It's not plugged in. And it's coming from the trunk lid, not the side. Also tried the jumping idea. No joy.

[GRSHOPR]

Does the smaller wire on the starter have voltage when you turn the key to start?

I assumed you meant the clip, so I checked, and no voltage. I also discovered something odd. Even with the key removed, it was still registering voltage to the starter. Actually, now that I think about it, that isn't odd, is it?? Isn't it connected directly to the battery? Oh, and there is a click in the dash, I assume one of the relays resetting itself.

[GRSHOPR]

OK, so I did some digging in the bay, and there is this connector, beneath the fuse box with the starter and headlight relays, that isn't plugged in. Check out the link below, for more details. I'm referring to pic number 1.

http://www.3sgto.org/showthread.php?1021-JDM-wiring-harness-issues

Update: I definitely think that this plug is to blame (I think this is plug A67, can anyone confirm?), but I can't find any sources or material on it to specify which plug it is or what to do with it. I'm thinking just match the colors up, as best I can, but I don't want to blow the motor up by randomly attaching wires, especially since the harness plug has 7 wires, and the body plug, 6. Can anyone shed some light on this thing that I might have missed? Thanks.

[GRSHOPR]

OK, so just to make sure, I went and connected my ground wire kit, and spliced the connector in for that plug. Still no change. I did however, find a relay just free hanging off the harness?? Any other ideas guys??

[CoreyB]

Have you crossed the big wire to the small wire on the starter to see if it starts ? Use a screw driver.

[Austin@STM]

The big wire should always have power. The small wire should only get power when the key is in the start position.

[GRSHOPR]

I'll try that tomorrow morning, but my headlights aren't working either. The fact that relays for both the starter and headlights are right next to each other in the fuse box is to suspect to be coincidence. Can you think of anything that would affect both systems?? I will absolutely try jumping the starter, but I'd just like to brainstorm in the meantime, since I think it'll turn over just fine. Thanks again.

[GRSHOPR]

OK, so I jumped the starter solenoid, and it turned over, no problem. Didn't start, but one problem at a time. So the starter and solenoid are for sure good, but the relay isn't getting any power to it, and I think the same issue applies to the headlights. Anyone know where I can acquire a JDM wiring diagram?

[GRSHOPR]

Hahahahahaha, so who wants to know what the problem was?? I feel like I deserve a slap across the face. Now that it turns over, it doesn't start. I KNOW timing is dead on. I'd be willing to bet the entire car that it is. Air obviously isn't a problem, with feathering the throttle. Which leaves spark and gas. I can't smell gas in the bay, and I can't tell spark tonight, since I can't be in two places at once, so I'll check spark tomorrow. You guys have any ideas of other things I should check?? There are no combustions, from any chamber. Thanks again for all the help.

[CoreyB]

Hahahahahaha, so who wants to know what the problem was?? I feel like I deserve a slap across the face. Now that it turns over, it doesn't start. I KNOW timing is dead on. I'd be willing to bet the entire car that it is. Air obviously isn't a problem, with feathering the throttle. Which leaves spark and gas. I can't smell gas in the bay, and I can't tell spark tonight, since I can't be in two places at once, so I'll check spark tomorrow. You guys have any ideas of other things I should check?? There are no combustions, from any chamber. Thanks again for all the help.

Yes tell me. Fuse ?

[GRSHOPR]

C31 wasn't plugged in. It was tucked up in there and I missed it when I was plugging everything back in.

[GRSHOPR]

OK, so it turns over, but won't start, like previously stated. Checked for spark and plug order, I KNOW timing is dead on, it's getting plenty of air. Which leaves fuel, which I don't smell in the engine bay. Any other things I should check for that could prevent it from starting??

[stealthee]

If your "fix" for your fuel pump housing issue doesn't have proper sealing you wont be able to build fuel pressure.

[GRSHOPR]

I suspected that'd be the case. Thanks Brian. The AN fittings arrive tomorrow. I'm going to redo it all correctly then. Another question about the pump assembly- say that some of the contacts were so rusted, that they broke off. What's the best way to replace those rivets that are on the top plate (the positive feed for the fuel pump and the ground are the two that broke off)??

[stealthee]

Its been awhile since I looked at a fuel pump assembly, so I can't give an honest opinion at this time.

[GRSHOPR]

OK. Thanks for the help anyways. Anyone else have an idea for that??

[GRSHOPR]

Anyone?? Bueller?

[GRSHOPR]

OK, so there is no power going to the fuel pump. I tested from the top plate with the key in START. What should I be looking at?

[stealthee]

I know you say it was in START, but were you cranking? Thats the only time power goes to the pump.

[GRSHOPR]

LOL, back to my terminology?? Yes, it was cranking.

[stealthee]

I only do that because a lot of people misuse the terminology. You need to check the test connector. You can also check the wire at the MFI relay. If I remember right its the blue/black wire. Its the same color as the wire that powers the fuel pump assembly.

[GRSHOPR]

And the MFI relay is hanging on the passenger side of the center console, right?? This could be the origin of the problem. The original MFI plug on the harness had 9 pins, instead of 8. Two of the wires were the same color, so I used the SWAG method to figure out which was which. I'll check and get back to you in a few if there's power to the MFI.

[stealthee]

Yeah, you need to see if power is getting to it, and coming out of it going to the fuel pump.

[GRSHOPR]

Which wire is coming in and which going out?

[GRSHOPR]

http://i881.photobucket.com/albums/ac18/Hackurs/IMG_0340.jpg

OK, so going from left to right, top row to bottom, the pin furthest to the left in the top row being 1, the next to its right being 2, etc.

Pin 1 (red and black wire)- Has power when the ignition is turned to START
Pin 5 (red and black wire identical to pin 1)- constant power whenever the key is in the ignition
Pin 6 (black and white wire)- same as pin 5

What I tried to do when I spliced in the new connecter for the MFI was match up the color of the wires, rather than just splicing them to their corresponding pins (1 to 1, 2 to 2, etc). The wires going to pins 1 and 5 were identical, so I used the SWAG method.

[stealthee]

Well like I said the blue/black wire goes to the fuel pump. Not sure which wire powers it off hand.

EDIT: I know the MFI changed at least once, maybe twice in the 3s line up. stealth316 MAY have something mentioned about the differences in MFIs

[GRSHOPR]

http://supercar-engineering.com/rubberducky/3S/Mods/TT/FPRewire/StockCircuit.html

Can you check out that link? If I'm reading it correctly (and I'd like to think that I am), the orientation by which I am holding the plug in my picture corresponds with the direction of the pinout? Is the "front" (pin side) or "back" (wire side) of the plug the correct orientation?

[stealthee]

Hopefully someone else can reply to that point. I usually have to study wiring schematics pretty hard to understand them and my mind is in a total fog so I can't 100% comprehend them at this moment.

[GRSHOPR]

Fair enough. Thanks for the help Brian. Hopefully this will be the last thing. Can anyone tell me which way is the correct way to look at a plug to correspond with wiring diagrams?? Wires or pins facing you?

[GRSHOPR]

OK, so by process of elimination, I figured out which it was. I then traced the wire. There is indeed voltage when the key is to START. And to remove any issue, I also bypassed the relay. There is indeed power to pin 5 on the socket as well, and in turn, via the bypass, pin 2. But there is still no power to the fuel pump. I don't here it priming or anything. What's next??

[Austin@STM]

if it has power for sure and its not turning on, you either have a grounding issue, a wiring issue at the pump, or you have a bad pump.

[stealthee]

OK, so by process of elimination, I figured out which it was. I then traced the wire. There is indeed voltage when the key is to START. And to remove any issue, I also bypassed the relay. There is indeed power to pin 5 on the socket as well, and in turn, via the bypass, pin 2. But there is still no power to the fuel pump. I don't here it priming or anything. What's next??

The pump doesn't prime. As I said it only runs when you are cranking the engine.

[GRSHOPR]

OK, so I shouldn't be hearing anything then anyways. I found another issue. Under the dash, by the passenger right knee rat's nest of wiring, I trace the power going from the relay to a plug that wasn't plugged in. Apparently, they changed the plug types from a normal 7 or 9 pin plug to one of those heavy duty ones for power transfer. I spliced in the correct plug, although there were two extra wires on the plug I spliced in that don't fit anywhere on the harness. No big at that point, because the pin I tracked the pump power to was spliced in and good to go. So where does the power head next?? Straight to the pump assembly? There still isn't power to that plug. And I thought the car can't turn over if that plug isn't plugged in?

On a side note, I found another plug in the center console, branches off right where the ECU plugs branch as well. It's black, has 4 pins, is covered in foam. What does that go to??

[GRSHOPR]

And I found something else odd. Somewhere between the pump and that connector, the wires change color?? The side coming from the relay, the power wire is blue and black. Leaving the connector, towards the fuel pump, it's black and red. And back at the fuel pump it's black and blue again?? Something isn't jiving here. I was thinking for a minute that maybe I spliced the wrong plug in, but looking at the original engine harness, that's the only possible plug that it could be. Plus the wires matched up. That can't be a coincidence. But it doesn't make sense why it would change colors and then change back. Or even WHERE it would do that.

[GRSHOPR]

OK, so I looked through my diagrams again. Here's what I've found.

Below is a 1991 diagram, which is what I'm using for a harness, and it's a little more in depth than the next pic, so it's a good start for comparison. Notice how the wires all the way back are b-l, or black and light blue, all the way to the fuel pump. I spliced in this morning what I'm pretty sure is C-30. This pic shows C-30 as being a 6 pin connector, which it was originally, on this 1991 harness. Which means I somehow have to find C-34, correct?

http://i881.photobucket.com/albums/ac18/Hackurs/1991.jpg

OK, so next is a pic of the 1994 diagram, since that's what the rest of my car is, aside from the engine harness. This diagram doesn't specify how many pins C-30 or C-34 have, so I think I'm going to have to take it on faith and luck that C-34 has the same number of pins between the generations. My bet is that I'll still have to splice in the newer connector. Notice also, how this diagram shows the wiring going from b-l (black and light blue), to b-r (black and red wire), which corresponds with what I'm seeing under the dash. Does all this seem logical and correct?? If not, please set me straight.

http://i881.photobucket.com/albums/ac18/Hackurs/Untitled.jpg

[CoreyB]

I would use the diagram to run your own wires to the pump.

[GRSHOPR]

My only concern is what does the dashed line around the fuel pump mean??

[GRSHOPR]

OK, so I said screw it, spliced anyways, and it's running!! Almost. It doesn't quite run on its own yet. If I turn the starter over for about 30 seconds, it builds up to about 2k rpm, but doesn't keep itself going yet. Is that normal?? It sounds like it's slowly building itself up to running, the combustions are getting deeper sounding, and building more quickly. But then I think the starter started to smoke, so I'm going to let it cool down for a bit before I try again. Is that normal?? Can a starter even smoke?? What should I be looking for to happen in the start-up process?? Admittedly, I haven't really dealt with an engine that has been sitting/new before. Not sure what to fully expect from this whole process. Any advice?? Thanks.

[CoreyB]

Can you check your fuel pressure ? Sounds like its to low. You should check the voltage at the pump while cranking as well.

You can also connect the blue terminal by the battery to the positive battery terminal and see if the pump is running. Thats the test terminal for the pump.

[GRSHOPR]

Can you check your fuel pressure ? Sounds like its to low. You should check the voltage at the pump while cranking as well.

You can also connect the blue terminal by the battery to the positive battery terminal and see if the pump is running. Thats the test terminal for the pump.

Are you sure about the blue terminal??? I connected it, and it threw a bunch of CELs, and it sounds like the MFI clicked, but I didn't see any power at the fuel pump.

[CoreyB]

Yeah. Something must be wrong. The blue one is for the fuel pump and the brown one is for setting ignition timing. Are you sure you jumped it to positive and not negative ?

[GRSHOPR]

Yeah. Something must be wrong. The blue one is for the fuel pump and the brown one is for setting ignition timing. Are you sure you jumped it to positive and not negative ?

Ha, again with the terminology! Yes, I double checked. It's the bright blue connector with a single wire, right?? Tapped it directly into the positive battery feed. Can there be a discrepancy because it's a 91 JDM harness/ECU/motor in a 94 USDM body?

[CoreyB]

Only if something is wired wrong.

[GRSHOPR]

What could be wired wrong? I only made 2 SWAG wire splices. At the MFI and at the fuse box under the hood (connector A67).

[CoreyB]

Maybe the wire that is supposed to be supplying power to the fuel pump from the MFI relay is actually tied to the wire that SHOULD be coming from the ECU to activate the coil in the MFI relay. Does that make sense ?

[GRSHOPR]

Yes it does. And that actually was it. I wound up going through my diagrams, discovered that the MFI SWAG had pins 4 and 8 reversed. So I respliced them, and made same progress. The motor turns over, and starts on its own. It keeps itself going for about 3 seconds, until I hear the MFI click, and then it dies. Thoughts??

[CoreyB]

Pull the ECU and look for leaky capacitors. Thats usually the problem when the MFI drops out.

[GRSHOPR]

That's what I thought. I pulled the ECU, and used my known good NA ECU. I know it won't run correctly, but it should at least run, and not cut out after a few seconds, right?? Anyways, it did the exact same thing with the other ECU in. No change.

[CoreyB]

Check all fuses. For some reason the ECU thinks you shut the ignition off. Also verifiy the grounds to to the ECU are all good. One other test is to disconnect the MAF and try to start, sometimes a bad MAF can cause problems like this.

You might also try unplugging the IAC and see if it stays running. A shorted IAC might shut it down when it kicks down from high idle.

[GRSHOPR]

Already tried the MAF. No change. Between the generations, the grounds from the MFI, wiring harness and one more from another source I'm not sure, were localized to one ground source. I was missing a ground in that localized point. I'm guessing it may be the ECU?? Maybe not?? There was a ground sticking out of the harness by the ECU plugs, but I'm not sure if that went to the ECU. Can you explain what grounds go to where on the ECU?? I have a developing theory, that maybe because the wires were spliced incorrectly, could that have ruined the MFI?? Are you talking fuses inside or outside?

[CoreyB]

The ground sticking out of the harness is likely a shield for the knock sensor wire, it goes nowhere. There is a diode in the MFI that could have blown from the wiring but I am not sure it could cause your problem. I believe the MFI is doing its functions properly.

If it was me this is the hillbilly test I would do. Disconnect the MFI, bend the little tabs on its metal cover and remove the cover. Plug it back in. You now can visually see the contacts for two relays. One powers the fuel pump, the other the ECU. Start the car while observing what the relays are doing. When the car dies, try to start again while holding one or both of the relays closed. In theory it should remain running. Now you need to figure out where the relay is losing its power or ground and why.

[GRSHOPR]

When I spliced in the MFI connector, I did it because the original plug had a 10 pin plug, and the MFI had 8 pins. However, what I did was take the wire that was obviously the ground for the MFI, and attach it to that central ground. Which means I think I removed the MFI's ground. Thoughts?

[CoreyB]

That would be my thoughts as well. When you turn the key to the run position the MFI will make one click and the check engine light will come on. Now when you turn the key off it should take a few seconds before you hear it drop out. If it drops out instanty the the ECU is not able to hold it closed, either because its bad or because of wiring. With my car, after you turn the key off it beeps three times and then you hear the MFI click.

[GRSHOPR]

Based on the picture below, would pin 2 be the ground?? Couldn't I just cut it and ground it to a ground point, or do I need to tap the ground into the ECU?

http://i881.photobucket.com/albums/ac18/Hackurs/Untitled-1.jpg

[CoreyB]

Pin 2 appears to send power to the ECU along with pin 3 with pin 6 being the ground source that closes the loop.

Edit, Actually I think pin 3 doesnt go to the ECU but powers the coils and other things. 2 would still be ECU power though.

[GRSHOPR]

So what would you recommend??

[CoreyB]

That would be my thoughts as well. When you turn the key to the run position the MFI will make one click and the check engine light will come on. Now when you turn the key off it should take a few seconds before you hear it drop out. If it drops out instanty the the ECU is not able to hold it closed, either because its bad or because of wiring. With my car, after you turn the key off it beeps three times and then you hear the MFI click.

Have you done this yet ?

[GRSHOPR]

It drops out instantly. I hear it prime when I put the key to the on position. Do you want me to try manually holding the relay in place?

[CoreyB]

If you hear the pump prime then 6 and 5 may be reversed. Are you sure its not just the surge valve under the hood you hear ?

[GRSHOPR]

No, it's for sure from the MFI. I don't hear the pump prime, I hear the MFI "prime", or click, I suppose would have been the better term. I hear it click when the key is turned, and then it clicks, and then the motor dies almost immediately. The MFI barely clicks first, but I'm sure it is clicking first followed by the motor, which makes me think it's cutting the fuel pump power.

What I don't understand, is the difference between the generations of MFI's. What wire did they delete in the later generation, causing the plug to change?? And if it is just the difference of a ground, where can I fix it?? It's gotta be as easy as splicing a wire.

[CoreyB]

But if you turn the key to run and dont start then turn it off does it click as soon as the key is turned off ?

[GRSHOPR]

No. It takes a few seconds to click again.

[CoreyB]

Gonna have to think about this. Sorry man doing my best here. I would try the holing the contacts shut thing but thats just me. If it does run I still wouldnt know what was causing it to not work properly.

[CoreyB]

but you could check to see if pin 8 always has power with the key on, even after it stalls. This will tell you its not the power to the MFI but the ECU not supplying the ground or the MFI itself. Have a hard time believing its the MFI though.

[GRSHOPR]

Dude, don't be sorry. You're being a huge help. I'll go try holding the contacts together, see what comes of it, and test pin 8 as well. Thanks again for your help!

[GRSHOPR]

Check out the diagrams a little further down in this link. What do you make of them?

http://www.3si.org/forum/f103/no-spark-no-fuel-please-help-372620/

[CoreyB]

That is about the resistor in the fuel pump system. I thought about this earlier but then moved on before mentioning it to you. There is a relay under the MAF that sends the fuel pump voltage through a resistor to limit is power, I believe during start up and the switches to no resistance. Its possible this is your problem. You may want nto try this. http://stealth316.com/0-frames.htm I dont think its whats wrong but suggest anyway. Gonna go look at those schematics better now.

[GRSHOPR]

I also found a pinout for my JDM ECU. Pin 8 is labeled as "MFI Power Supply Ground". It's description is "Used to pull MFI Relay for fuel pump". So, I'm thinking of checking out to see if the ground out from the MFI is wired to that, but the question remains, which pin is the ground out on the MFI?

EDIT: On page 7 of this thread, look at the schematic that I posted there, paying attention to where pin 5 on the MFI heads to..... What do you think??

[CoreyB]

Pin 5 is the ground supplied from the ECU for the fuel pump relay in the MFI. Pin 6 is the ECU supplied ground for the MFI that supplys power to the ECU and other parts.

[GRSHOPR]

So if it IS a failure to ground, and if pin 5 is wired correctly (which it is), then would the next thing to verify by the ground for the ECU itself?? Would it stand to reason that it can't ground the MFI if it itself is not grounded properly?

Edit: I see three chassis grounds for the ECU (pins 13, 26, and 71), one on each plug. Those are the ECU grounds, right?? And if they aren't grounded correctly, then the ECU can't ground the MFI?

[CoreyB]

Well I understand you thought but the ECU is bolted to ground. And the fact that the ECU closes and then holds the MFI for a amount of time tells me it is able to supply that ground when it wants to. This tells me that for whatever reason the ECU is giving up the ground or the power is being pulled. I am leaning towards the ECU having a issue. I just dont know for sure.

[GRSHOPR]

This is a pic of the old plug for the MFI. Pin 6 on this diagram indicates that it's the ground. It's the only black wire on the entire plug. But where does it go to??

Edit: And is it just me, or does it look like in this pic that pin 6 is an outside ground for that relay in addition to the ECU ground??

http://i881.photobucket.com/albums/ac18/Hackurs/Untitled-2.jpg

[GRSHOPR]

Well I understand you thought but the ECU is bolted to ground. And the fact that the ECU closes and then holds the MFI for a amount of time tells me it is able to supply that ground when it wants to. This tells me that for whatever reason the ECU is giving up the ground or the power is being pulled. I am leaning towards the ECU having a issue. I just dont know for sure.

I would have thought ECU as well, but I tried a known good NA ECU, that, while it wouldn't function properly, will, if I understand correctly, at least keep the motor going. But the exact same thing happened. Which makes me think that there's a ground missing somewhere. But the question is where? Why would the old MFI have a ground and the new one not?

[CoreyB]

It seems that pin 6 runs a alternative coil for the fuel pump relay. I do not know what it purpose is. What MFI are you using, the one in this schematic or the one for a 91 model ? You might try tying pin 6 in with pin 7 on this diagram.

[GRSHOPR]

The one right above is the 91 wiring diagram, and the one on page 7 is from the 94. I'm thinking you're right. Pins 7 and 6 should be spliced together to create a proper ground, which would explain the issue here. The wire orders change from 91 to 94, so I posted them both to compare. I'm going to ground pin "7" (in reality, pin 5), and see what happens.

[GRSHOPR]

ROFL. OK, so I grounded it, and it starts up, revs really high, dies, and then I can hear what I think is the fuel pump (only motor in that area) kicking into overdrive, and continuing, until I pull the key out.

[CoreyB]

Yeah thats because you GOUNDED the pins to the MFI lol. The ground is to be supplied by the ECU to pin 7 not tied to ground itself. I think the problem is with pin 8 not holding ground from the ECU try grounding that wire and see what happens.

[GRSHOPR]

No change. Lol, should I just start grounding out every pin?? I did your "hillbilly" method, and I got it to run constantly, by holding down one of the relays. One relay goes, then the other follows, thus causing the fuel cut. The first one to go is NOT the fuel pump relay. It's the other one. Where does that lead to?? Also, when I was holding it down, the RPM's kept creeping higher and higher. I figured at 2500 RPM's, I should stop it. What's causing that? Could it be the resistor pack for the injectors?? First things first though. What does the other relay control?

[GRSHOPR]

Here's a stupid question. On the 94 MFI diagram (page 7), is pin 3 (red wire) grounded to a common ground?? Is that what I'm seeing?? If that's the case, should I try grounding it??

[CoreyB]

The other one is for pin 8 to the ECU. Its the one I suspected. I dont know why the rpms are climbing, thats a different issue. Was this car a TT to start with ? The relay in question supplys power to the ECU which the ECU supplys the ground to pin 8 to get. I have no idea why or what the power is needed for.

[GRSHOPR]

OK, so I'm kind of confused now. Are you referring to pin 8 on the MFI or the ECU?

[CoreyB]

Mfi...

[CoreyB]

Pin 7 is not a ground. it is 12v positive, at least thats how I see it.

[GRSHOPR]

Just wanted to make sure. I was confused as I was looking at the 94 diagram, and then realized you were looking at the 91 diagram. Moving on though. Pin 3 (or 5, on the 91 diagram), should be straight grounded, correct?

If the ECU power is the issue, is there a way to bypass the relay??

[CoreyB]

When pin 5 of the mfi is grounded it energises the coil for the fuel pump relay. This then sends power to pin 1, which goes to the fuel pump. When looking at these schematics think of it as if the coil is in the pic is both grounded and has power it will pull the little switch toward it.

[CoreyB]

Nothing on the MFI is straight grounded. Only grounded through transistors in the ECU.

[GRSHOPR]

But on the 91 schematic (page 9), the black wire at pin 6 was straight grounded, wasn't it?? If not, where does that lead to?? I ask because pin 7 on the same diagram heads to the ECU.

[CoreyB]

Off of which diagram ? lol my head hurts. Post the diagram you are talking about and I can answer which pin does what.

[GRSHOPR]

OK, so this is the 91 diagram. Notice how pin 5 (red wire) seems to be grounded?? Same with pin 6 (black wire)??

http://i881.photobucket.com/albums/ac18/Hackurs/Untitled-2.jpg

Now this is the 94 diagram. It looks like they removed the ground for the fuel pump relay (black wire), and left just the ECU ground (red wire). My question is, are those two wires straight grounded?? Because it doesn't look like they go to the ECU. It looks like pins 2, 5, and 6 go to the ECU on this diagram, but not pin 3. Am i correct in this??

http://i881.photobucket.com/albums/ac18/Hackurs/Untitled-1.jpg

[CoreyB]

You are correct that pin 3 does not go to the ECU, however this is not a ground but power which also goes to pin 2 which does goes to the ECU.

In the first pic pin 5 I dont believe to be grounded. I cant tell where it goes to but it is likely supplying power to something.

Pin 6 is getting a ground from somewhere but I dont know where or why. It does the same thing as pin 7 on the mfi, all from the first pic.

Second pic, pins 6 and 5 are ECU supplied grounds pin 2 is power to the ECU.

Hope some of this makes sense. Last post tonight but would be willing to help in the morning. Hope I have been at least some help so far. Its difficult when you cant personally be there to work on it.

[GRSHOPR]

It does indeed. Thanks for you help and staying at it. I'll post updates, but hopefully I'll have it fixed by tomorrow. If not, we can have more "fun"!

[GRSHOPR]

But I got it!!! I had pin 9 from the first diagram wired to pin 8 on the second diagram, instead of jumping pin 4 to pin 8!!!! She runs!!!!!!!!!!!!!! Thanks for your help!! Couldn't have done it without you!!

[CoreyB]

Thats great news man.

[GRSHOPR]

Thanks again for all your help. Now for the tuning phase!

Here's what I've seen so far:

-at what water temp does the radiator kick on?? The water hit 200, and it never turned on. I turned on the A/C, and the driver's side side nothing either.
-it idles at 1200 RPM, even with the ECU reset, and the idle control screw turned all the way clockwise (decreasing RPM's)
-white smoke coming out of exhaust. It DOES have a walbro 255 on a stock FPR. That might do it right?? Unburned fuel?
-my UEGO fluctuates pretty wildly when the engine revs, upon acceleration, it hits about 12-13, and at idle, slowly creeps back up to 17+. Having never owned one before, is that normal??

[CoreyB]

I think the fans should have come on, definitly with the A/C. Check the fuses, I think at least one of them is under the hood on the drivers side. You should also check that they are plugged in. The coolant temp sensor for the fans is on the water neck.

It sounds like the ECU is not getting the coolant temp signal. It thinks the engine is always cold causing the high idle and lack of fans. The walbro has nothing to do with the running rich or high idle, you get a little better flow capability with it but it wont over run the fpr or the injectors.

You shouldnt adjust the idle screw with out setting the TPS at the same time. The TPS has a switch in it to tell the ECU you are at closed throttle, when you make the adjustment it can make it so you never hit the switch or it opens late into giving it throttle. Try loosening the two 10mm bolts the holds the throttle cable to the intake plenum, it is on a slide adjustment and its possible its holding the throttle open.

[GRSHOPR]

Ah, but I have a 94 body and a 91 harness/ radiator. where should I tap the signal for the coolant temp sensor for the radiator?? On the radiator where the sensor is, or on the water neck?

[CoreyB]

Check for power at pin 5 of the radiator high and low relays. The plug is shaped like a T 5 being the bottom of the T. They are located in the fuse box under the hood passanger side.

I was mistaking about the water neck sensors controling the fans. Seems they dont.

[GRSHOPR]

There were 4 pins in each relay, and there was power to all the pins but the middle one in each relay.

[GRSHOPR]

Also, i drove it around the block to test it out- it dies when I brake?

[CoreyB]

Sitting still hitting the break, what happens ?

[GRSHOPR]

Nothing. I think it's because the TPS hasn't been adjusted yet. When I brake while moving, the RPM's drop down and don't recover.

[CoreyB]

Sounds like the IAC is not working. At idle, when you turn the wheel or turn the A/C on the idle should increase. If it doesnt then check out the IAC asap, bad ones are well documented as destroying ECUs.

[GRSHOPR]

The idle does increase. I replaced the IAC a couple months ago. I know it's good.

[CoreyB]

There were 4 pins in each relay, and there was power to all the pins but the middle one in each relay.

There are 5 spots for pins but only 4 pins correct ? The middle one is pin 4, it is on the switched side of the relay and wouldnt have power without the relay being in and active. You could check that you have a ground at pin 1 of the 6 pin plug at the radiator, should be passenger side of it IIRC. Also the fans wouldnt come on with the A/C unless the A/C works.

[CoreyB]

The idle does increase. I replaced the IAC a couple months ago. I know it's good.

Thats good to know.

[GRSHOPR]

There are 5 spots for pins but only 4 pins correct ? The middle one is pin 4, it is on the switched side of the relay and wouldnt have power without the relay being in and active. You could check that you have a ground at pin 1 of the 6 pin plug at the radiator, should be passenger side of it IIRC. Also the fans wouldnt come on with the A/C unless the A/C works.

There are only 4 pins on each relay. And the radiator had a 6 pin connector, but the harness for it didn't (it had 4 pins), so I had to splice in the 4 pin connector, leaving 2 extra wires. These two wires lead to the coolant temp sensors in the radiator. I just don't know where to splice them in for the radiator/ECU.

[ntcmpjg]

i read all 12 pages my head hurts and im never doing a TT swap. Nice project you have their, did you make sure to change to the 91 crank angle sensor and not the 93+ Cam angle sensor because you put the ECU from the 91 in it. just thought I would ask

[CoreyB]

OK, on the radiator side pin 1 is ground and is the black wire from the harness.

[GRSHOPR]

i read all 12 pages my head hurts and im never doing a TT swap. Nice project you have their, did you make sure to change to the 91 crank angle sensor and not the 93+ Cam angle sensor because you put the ECU from the 91 in it. just thought I would ask

The 91 motor came with the proper CAS. I didn't have to touch a thing. The right one is in.

[CoreyB]

i read all 12 pages my head hurts and im never doing a TT swap. Nice project you have their, did you make sure to change to the 91 crank angle sensor and not the 93+ Cam angle sensor because you put the ECU from the 91 in it. just thought I would ask

He has a 91 engine.

[GRSHOPR]

OK, on the radiator side pin 1 is ground and is the black wire from the harness.

OK, so green is ground. Seems standard. But where does the red wire (pin 4) head to? And can I just ground pin 1 straight up, or do I need to ground it to the ECU?

[CoreyB]

This might help you.

[CoreyB]

Straight ground.

[GRSHOPR]

OK, so we are looking at pins 3 and 6. Those are the two extra wires.

[CoreyB]

Ok. Both of those wires are used to provide ground from the sensors to the coils in the relays, this is your problem. On the high and low relays these are the pins you didnt measure power on.

[GRSHOPR]

Honestly, I'm fried from looking at so many diagrams. I'm confused by the fact that the wires from the thermo sensor don't correspond to what is in my bay in regards to their color, so I'm going to go through this step by step. Can you proof my thought process, to make sure I'm not going crazy??

Connector A-55 is the plug off the radiator. The two extra wires from the 6 pin plug were on one of the far sides of the plug, top and bottom of each other. That means they would have to be pins 1 and 4, or 3 and 6. The problem I have with that, is that per the diagram, pins 3 and 4 both power the fan. I checked the physical wires, and they do correspond. The light blue wire with yellow (pin 4) and the light blue wire with black (pin 3) do go to the fan motor, not the sensor. There are 2 black wires (grounds), on the radiator side of the plug, and only 1 on the harness side. In lieu of a black wire, there is a red-black wire. And that's as far as I've gotten. is that right?? Can you complete the puzzle?

[CoreyB]

Pin 4 powers/grounds the fan, pin 3 is to ground the coil in the same fans relay. This is the low relay, hence the resistor. The radiator side of things doesnt acually power anything, it supplys grounds. You should have 2 wires from the harness that will have 12v on them, these go to 3 and 6.

[GRSHOPR]

I only have 1 wire with power to it, and that is pin 2?

[GRSHOPR]

AHHHHH. We are making a grave assumption here, and I am wholly to blame. This radiator is a 1st gen, but there's no way it could be a 91, based on the wire colors. Let me figure out exactly what year it is.

Edit: It doesn't matter what year it is, all the wiring is the same. None of them show a straight red and straight green wire on the male side (radiator side) of plug A-55. I don't get it.

[CoreyB]

According to the schematic that is only possible if the coil in the low relay is bad, and the one with the power would go to pin 6 on the radiator. Pin 2 of the radiator should be empty.

[GRSHOPR]

According to the schematic that is only possible if the coil in the low relay is bad, and the one with the power would go to pin 6 on the radiator. Pin 2 of the radiator should be empty.

It may have been pin 6 originally, but I may have wired it incorrectly. I don't think there is supposed to be constant voltage to all but one of the pins in the radiator relays.

[GRSHOPR]

OK, so I jumped pins 4 and 5 on the low fan relay, where the signal should connect and start the fan. Nothing. I checked the plug again, and only 1 pin had power to it still.

[CoreyB]

There should be power to all but one of the pins on the relay but only if the relay is plugged in. If its out there should be power to two of them. Provided the fan can feed power to the gound pin when not grounded.

[CoreyB]

OK, so I jumped pins 4 and 5 on the low fan relay, where the signal should connect and start the fan. Nothing. I checked the plug again, and only 1 pin had power to it still.

That shouldnt work. If you ground pin 5 the fan should run though. At least it wont work if the harness at the radiator is wrong or the sensor isnt hot enough.

[GRSHOPR]

OK, so now there's no power to pin 5. I did cut the two wires the weren't part of the plug, to see what that would do. Can't remember why now. But the oddest thing happened. When I turned off the car, and turned the key to the ON position without starting it, the fan turned for a few seconds....??

[GRSHOPR]

I remembered why I cut those wires. I was testing them for power. One did have power. Should I assume that power line should be attached to the radiator plug??

[CoreyB]

I would say it goes to pin 6 of the radiator but its hard to say. Where is the wire leading to ? If it goes to pin 3 of the high relay then yes it goes to pin 6 of the radiator.

[GRSHOPR]

It's coming off the harness. Not sure where it's coming from. Unfortunately, it happens to be the same color as another wire in that bundle. I used the SWAG method to choose which was which.

[CoreyB]

You could test this with a ohm meter and the relay removed. Hold one of the meters leads to the cut wire, the other put in pin 3 of the high relays socket. The relay must be remove to check. If you have continuity then its the right wire.

[CoreyB]

Whats SWAG ?

[GRSHOPR]

Scientific Wild Ass Guess. OK, so I was mistaken before. I misread the signs. Both pin 5's are being fed by a wire on the plug. It's red and black going in from the harness side, and blue and green (i think?? it's definitely not the blue and black wire, but I can't discern any yellow or green marks on it. I'm pretty flipping sure it's the green one though. green is more subtle and harder to see than yellow on these wires) coming out the radiator side. It stands to reason, then, if this is true, that up to both pins 5 is correctly wired.

Edit: And you were right. There are 5 pins on the relays, but pin 2 is small, it's easy to miss.

[CoreyB]

Pin 5's of the high low relays in the main fuse box on the passanger side correct ? They should not have power on them unless the fan motor can send its power to the ungrounded ground wire. That wire should be the switched ground wire for the fan. If this is the pin 5 on the correct relays then touch it off ground and the fan should spin.

[GRSHOPR]

OK, so on the relays (hi and lo) in the diagram, it looks like pin 1 on both of them is fed from the same source, correct?? Or is it just the low?? Aside from the voltage that is correctly (supposedly) feeding pins 5, how many other power supplies are there into this circuit? One or two more?

[GRSHOPR]

Which they don't. Which means either pin 5 is fed wrong, or there is no other power getting to the fans, right?

Edit: Why, if I were to jump pins 4 and 5 on the Lo relay, should the fan not start up?? Isn't that the same as bypassing the coil in the relay that's normally fed by pins 1 and 3?

[GRSHOPR]

Check out this link. His pics for the radiators are further down the page since they are gone from the original post. What do you think of that?? Those are the exact wires that I'm having an issue with. But I didn't think they were grounded. I'm going to have to go trace the ground in the plug I think, since both grounds are in the plug.....??

http://www.3si.org/forum/f53/1g-harness-2g-body-274771/

[CoreyB]

This explains why I am stumped.

3. Radiator fans
On the 1g cars, the fans are controlled by 2 switches mounted in the radiator, on 2g cars they are controlled through the ecu. This is how i wired them without modification to the fan harnesses, and keeping the 2g fans with a 1g tt radiator.......Take the black wire from each switch, tie them together, and attach a grounding lug to them. Next take the other wire from each switch and run them into the passenger compartment to connector C-29 near the blower motor. tie these wires into pins 3 & 11 of C-29 (pin 3 high, pin 11 low). Heres a couple pictures of how i did it. I chose to use another weather pack connector from NAPA so the connection can be unplugged to remove the radiator without cutting any wires.

I have been looking at a 91 schematic all this time. Still confused though. If you dont fix it before I get home I will pull up schematics for the 94 and compare then walk you through it.

[GRSHOPR]

I'm writing a paper right now that's due in 3 hours, but I hope to have it finished sooner so I can run those wires real quick. I will still need your help. I am thoroughly confused now about the other 4 wires, the ones that DON'T connect to C-29. Two are black, which I suspect I am to ground, but that leaves 4 pins for the 2 blue wires on the radiator side.

[GRSHOPR]

OK, paper is done. Off to go ground the black wires and run the wires to C-29. I'll let you know how it turns out.

[GRSHOPR]

And I got all but the two wires for C-29 in. I have to go to class now, but I'll be back about 9. I'll post then to let you know I'm back, and then I'll go splice in those wires, see what happens.

[GRSHOPR]

I'm home, going to go splice in those two wires. I'll let you know how it goes.

[GRSHOPR]

Heh, I can't go any further. Mainly because- which wire is HI and which LO??? Can't find any indication which goes to which pin.

[GRSHOPR]

OK, found the answer ( I think. cross your fingers, the motor is warming up now.). Now my next issue is the idle. I adjusted the TPS, and it's still idling at about 1100. Any other ways to reduce the idle?? The idle screw is "turned down" as low as it will go.

[GRSHOPR]

And the test was a no go. The fan never turned on. I turned off the motor at 185 degrees. And just for shits and giggles, I measured the relays at pins 5. There is no longer power to them, which is probably the issue. I believe the walkthrough for the red and green wire, but that just leaves the issue of power to the damned relays and fans. Anyone got any input on this one?

[CoreyB]

Not sure. Keep in mind though that the link to 3si was using a 94 radiator I believe.

You may have a vacuum leak causing the high idle.

[GRSHOPR]

I'm pretty sure I do have a vacuum leak. I can hear air whistling at the TB, but I can't find the leak. I can deal with the slightly elevated idle for now, the biggest thing is the radiator. Are you SURE there should be power at pin 3 in the relays?? Doesn't that prohibit the flow of power through the circuit from pin 1 to pin 3?

Edit: OK, WTF. Now there is power to pin 5. Regardless, shouldn't there be power to only pins 1 and 5, since pins 4 and 3 head to ground??

[CoreyB]

Pin 3 should have power to it ONLY if the relay is plugged in and the radiator switches are not closed. But thats for a 91 relay setup. Not sure what you are using ?

[GRSHOPR]

It's a 94 box. But the principal is the same. Below I posted the 94 schematic. Then the issue is that there is power being supplied to pin 3 of the relays, but from where?

http://i881.photobucket.com/albums/ac18/Hackurs/Untitled-3.jpg

[CoreyB]

Ok, here is my take on this.
Pin 3 of the low relay needs to go to pin 3 of the radiater, currently would go to pin 6 on the to the ECU on the old harness.
Pin 4 of the low relay needs to go to pin 4 of the radiator, on old harness it would go to a resistor.
Pin 1 of the hi and low relays should have 12v.
Pin 3 of the low relay should go to pin 6 of the radiator, on the old harness it went to pin 53 of the ECU.

Ground pin 1 of the radiator. Now if you have power to one side of the radiator fans this should work. Test would be jumping pins 4 and 5 of either relay.

[GRSHOPR]

Based on what you're saying, is electricity flowing from the top to bottom of the page, or from the bottom to the top? And I'm thoroughly confused. It goes to pin 53 of the ECU now. The diagram 2 posts up is the 94 model.

[CoreyB]

You have 91 ECU correct ? It doesnt control the grounds for the fan, the radiator now does that. Basically in the 94 the ECU does the work of the radiator plug on the 91 diagram.

[GRSHOPR]

Gotcha, so it's independent of the ECU. Another oddity, since I just love coming up with more problems. On the LO relay, the pin with the lower voltage, due to the resistor, is pin 1....?? Pins 3 and 5 both have the full 12V. Does that sound right to you, since I can't see how the resistor would even be connected to pin 1.

Edit: But following that walkthrough from that link I posted earlier, the wires for the temp switches I ran into the body, and tapped them into lines that run directly into the ECU.

[GRSHOPR]

Based on that fact, couldn't I just ground pin 3 on both relays and that'd do it? Because power is being fed correctly to the fan from pin 2, and heading out via pin 5 to the pins 5 on the relays. It just seems like the relays are having issues with a ground between pins 1 and 3.

[CoreyB]

Provided pin 4 0f the relays has ground and pin has 12 volts then grounding pin 3 will activate the relays and turn on. But will not shut off.

[GRSHOPR]

And it didn't even turn them on. Which pin should have 12 volts?? At this point, I'm thinking about a hotwire.

[CoreyB]

Sorry pin 3 should have 12v. Just ground pin 5, if they dont come on then, then the fan eiother doesnt have power, Pin 5 doesnt really connect to the ground of the fan or the fan doesnt work.

[GRSHOPR]

OK. I'll see what that does.

[GRSHOPR]

Grounding pin 5 did nothing. Should I ground pin 5 on the HI relay as well??

[CoreyB]

They are conected so it shouldnt matter, you can try it though. If it doesnt work the do a continuity test from pin 5 to the fans ground terminal, and verifiy that the fan does have 12v on its other terminal.

[GRSHOPR]

It doesn't. At this point, I'm fed up, and I'm just going to hotwire it for a few days, til I can figure out the issue. I'm thinking splice together the two power lines for the fan motor, and the grounds?? That should do it, right?? There is definitely power going to the fans.

[CoreyB]

Just ground the fans ground terminal. Make sure that the fans power is switched though so the turn off with the key.

[GRSHOPR]

Yeah, didn't work. I'm gonna splice the black wires and ground them and splice the blue wires together to the power source.

[GRSHOPR]

Actually, I discovered what may have been the culprit all along. I broken solder joint! So, just for the hell of it, I left the fan plug ground straight grounded, and grounded pin 5. The damn thing worked! go figure. I'm warming the engine up now, to see if that fixed the entire issue.

[CoreyB]

LOL, figured it should work if pin 5 really went to the fan.

[GRSHOPR]

Which it always did, but I suspect that the ground may have been messing with it.

[CoreyB]

Sounds like it went to the fan but wasnt making a connection at the fan.

[GRSHOPR]

Nope. Still no fans, at 185. I'm gonna pull the battery, to reset the ECU.

[CoreyB]

Now that you now they work when grounding pin 5, dont give up. Do this.....




Ok, here is my take on this.
Pin 3 of the low relay needs to go to pin 3 of the radiater, currently would go to pin 6 on the to the ECU on the old harness.
Pin 4 of the low relay needs to go to pin 4 of the radiator, on old harness it would go to a resistor.
Pin 1 of the hi and low relays should have 12v.
Pin 3 of the low relay should go to pin 6 of the radiator, on the old harness it went to pin 53 of the ECU.

Ground pin 1 of the radiator. Now if you have power to one side of the radiator fans this should work. Test would be jumping pins 4 and 5 of either relay.

[GRSHOPR]

I don't get what you're saying. use the wire colors. The pins don't correspond anymore, aside from the red and black going into A-55 from the harness side, and the blue and green wire, also harness side. The big issue seems to be matching up radiator wires to harness wires in plug A-55.

harness side wires: black, red and black, blue and yellow, blue and green
Radiator side wires: Black (goes nowhere, it's been straight grounded), blue, blue and black, and another black.

[GRSHOPR]

That doesn't work anyways. Pin 3 and 6 on the radiator no longer "exist". They're the ones spliced into the ECU.

[CoreyB]

Why would they be spliced into the ECU ? If its the 91 ECU it has no fan control. Those pins are the ones that go to the thermal switches on the radiator to turn the fans on.

[GRSHOPR]

Exactly. They're spliced into the ECU to the EGR pins, which essentially do the same thing. Check the link out again. That's where he ran the red and green wires, or pins 3 and 6.

http://www.3si.org/forum/f53/1g-harness-2g-body-274771/

[GRSHOPR]

And with the grounding of the pin off of A-55 has come a new issue. There is no power to pins 1 or 3 on both relays. That means that the temp switches are working correctly, and grounding when the engine gets hot enough, but there's no power getting to pin 1 for the relays to close.

[CoreyB]

Blown fuse. Its a 10A fuse. Think its under the dash. Print says its #3 not sure if thats right or not.

[GRSHOPR]

Nicely done!

[GRSHOPR]

No change though. And the weirdest damn thing happened. I turned the ignition to ON, and the damned AC fan started up? Then I started the car. And it turned off?

[CoreyB]

You dont still have connections going to the ECU do you ? If you do it would just blow that fuse again. 53 an 6 can not be hooked up to that ecu.

[GRSHOPR]

I do. And the fuse still hasn't been blown. Pins 3 and 6 are in no way associated with the relays or power from the relays. THey're just 5V. And now I can't jump pin 5 to start the fan anymore....?? The power to it is weak and erratic.

[GRSHOPR]

And now it's strong and holding steady??

[CoreyB]

Can you tell me what pins you are spliced to on the ECU ?

[GRSHOPR]

C-29, pins 3 and 11. They lead to pins 6 and 53 on the ECU

[GRSHOPR]

ROFL. The DRIVER'S side fan kicks on when the temp hits 190, brings it back down to about 182.

[GRSHOPR]

Here, look at this. This is essentially how and why it was spliced in for the 94 body.

http://i881.photobucket.com/albums/ac18/Hackurs/Untitled-4.jpg

[CoreyB]

Pin 53 on the ECU is for the EGR temp sensor, and pin 6 is for the EGR solinoid valve. Pin 53 is a 5v signal wire. You do not want it hooked up like that, thats very bad.

[CoreyB]

I understand, but that pic is of a 94 ECU. You 91 doesnt have those two transistors in it that ground pins 3 of the relays, instead you are sending 5v and a ground signal from pin 6 of the ECU that would normally run the ECR solenoid valve.

[GRSHOPR]

I don't understand why or how that guy pulled it off like that in his thread. Obviously it worked for him, and he used a 91 ECU/harness in a 94 base. EXACTLY what I'm doing. How did he pull it off?

[GRSHOPR]

Hey Corey, I'm gonna start a new thread. This one has gotten way too long, and I am utterly confused in the last 3 pages. I'll just unclutter it all with a new thread.