Special problem pulling engine codes (Experts Only)

[ibsorgn]

Can any of you rocket scientists tell me how to pull engine codes from a 2gen 3000GT (OBD1 Hybrid) running a 1st gen ECU. For second Gens the procedure is to short out pin#1 and turn on the ignition and read the flashing codes from the engine check light. 1st Gens you jump pins #10 and #12 and read the voltage deflections from pin #1.

My only concern is don't like the idea of shorting out #1 on the OBD hybrid as it may cause a problem using this mixted configuration.

Appreciate any replys especially from you TT conversion folks.

[RealMcCoy]

What year is the car? what part # ECU? have there been any wire harness changes?

[ibsorgn]

What year is the car? what part # ECU? have there been any wire harness changes?

1994 3000GT SL NA 6G72 which I installed a supercharger on. Wiring is a standard 94 NA harness. This, btw is a all Fed spec car. ECU is a 92 Fed spec TT ecu model was
either MD159966 or MD190663, can't remember I think it was a 9966. No wiring harness changes made other than eliminating a couple pins to make the unit operation. I did however split the O2 signal to feed the two pins required by the ECU. I might add I wired in zener diodes to surpress any possible signal feedback for each o2 pin.

Motor has been running fine for over 2 years but I recently received an engine check light . I have my ideas on what to do but I don't want to say as I don't want to influence anyones replies.

[RealMcCoy]

Pins 112 and 113 (yellow and pink wires) are identical on the 94 NA and the 92 TT ECU connectors. The yellow wire is pin 1 on both style diagnostic connectors.

I don't understand where you got the code gathering info you posted for the first gen? was that a typo? the manual says use an analog volt meter, (I use my 1K Ohm resisted LED lamp) between pin 1 and pin 12. (Actually any ground will work, it doesn't have to be pin 12) So to check codes on your car you would do the same. You would hook the voltmeter between pin 1 and ground, and count the pulses...

[ibsorgn]

Pins 112 and 113 (yellow and pink wires) are identical on the 94 NA and the 92 TT ECU connectors. The yellow wire is pin 1 on both style diagnostic connectors.

I don't understand where you got the code gathering info you posted for the first gen? was that a typo? the manual says use an analog volt meter, (I use my 1K Ohm resisted LED lamp) between pin 1 and pin 12. (Actually any ground will work, it doesn't have to be pin 12) So to check codes on your car you would do the same. You would hook the voltmeter between pin 1 and ground, and count the pulses...

My car is equipt with the OBD2 style (16 pin) port however it is normaly referred to as the OBD1 Hybrid. The procedure for OBD1 came from Stealth316.com, We are on the same page for pulling codes on Gen 1s maybe just stated a little different. So are you saying just follow the Gen 2 procedure?

[stealthee]

You put pins 10 and 12 in your initial post. The correct pins on 91-93 is 1 and 12, but as McCoy said, 12 is just a ground and the pins on the ECU are the same, so yes, use the hybrid "paper clip" method and you will get your codes.

[ibsorgn]

Pins 112 and 113 (yellow and pink wires) are identical on the 94 NA and the 92 TT ECU connectors. The yellow wire is pin 1 on both style diagnostic connectors.

I don't understand where you got the code gathering info you posted for the first gen? was that a typo? the manual says use an analog volt meter, (I use my 1K Ohm resisted LED lamp) between pin 1 and pin 12. (Actually any ground will work, it doesn't have to be pin 12) So to check codes on your car you would do the same. You would hook the voltmeter between pin 1 and ground, and count the pulses...

You know what? I don't know where I came up with the pin#10 thing! I think I got confused reading various pubs and comments. I checked back with the J. Lucius site and you're correct. It was not a typo, more of a brain fart.

[ibsorgn]

You put pins 10 and 12 in your initial post. The correct pins on 91-93 is 1 and 12, but as McCoy said, 12 is just a ground and the pins on the ECU are the same, so yes, use the hybrid "paper clip" method and you will get your codes.

Sorry I don't know what the Hybrid paper clip method is? My concern is one of grounding out pin #1 as that is the pin that is used for sending signals for 1st gens. If in fact the signal is being sent to pin #1 and I ground it, I may wind up shorting something out. If pulling codes for my 1st gen ECU and 2nd gen harness configurations follows the normal 2nd gen procedure then I'm good. (ie, gound pin #1 and watch the engine "check engine" light.

As a after thought, In my configuration, do you think it might be possible to get a signal from pin #1 by using a volt meters probe's on pin#1 for (+) and the other probe to any ground (-) or is it strickly a flashing EC light situation?

Last question, do you have ECU, Harness configuration like mine?

[RealMcCoy]

My car is equipt with the OBD2 style (16 pin) port however it is normaly referred to as the OBD1 Hybrid. The procedure for OBD1 came from Stealth316.com, We are on the same page for pulling codes on Gen 1s maybe just stated a little different. So are you saying just follow the Gen 2 procedure?

No, I'm saying you use the 1st gen procedure with the voltmeter... The ECU You have doesn't flash the CEL for codes. The only change you will make in the procedure, is you will be hooking the positive lead of the meter to pin 1 of the OBDII style connector rather than pin 1 of the OBD1 connector.

[ibsorgn]

No, I'm saying you use the 1st gen procedure with the voltmeter... The ECU You have doesn't flash the CEL for codes. The only change you will make in the procedure, is you will be hooking the positive lead of the meter to pin 1 of the OBDII style connector rather than pin 1 of the OBD1 connector.

OKay, I'll give it a try after this rain storm finishes. BTW, I assume the negative lead to any ground as pin#12 on my ODBII port may not be a ground.

[RealMcCoy]

OKay, I'll give it a try after this rain storm finishes. BTW, I assume the negative lead to any ground as pin#12 on my ODBII port may not be a ground.

Yes... I'm sure there is a ground wire in the ODDII plug, but I haven't researched it, so I have no idea which one it would be...

Edit: I must be bored... I just looked it up. Pins 4 & 5 are ground wires in that plug.

[ibsorgn]

I just spent the last hour attempting to pull the codes following your suggestions. Using a voltage meter set on 10v I hooked the (+) lead to pin#1 and the (-) lead to the chassis ground. Turned the ignition key 2 clicks (run) and got a constant voltage but no deflection. This was your recommended procedure, or did I do something wrong? Surely I'm not restricted to using an OBD port ground!

[RealMcCoy]

Are you using an ANALOG volt meter? or a digital volt meter? A DVOM has way too much internal resistence for the ECU to recognize the draw and know it's there...

[ibsorgn]

Are you using an ANALOG volt meter? or a digital volt meter? A DVOM has way too much internal resistence for the ECU to recognize the draw and know it's there...

Analog

[RealMcCoy]

You're confident you've correctly identified pin 1? can you tell if it has a yellow wire?


http://i90.photobucket.com/albums/k252/lnmccoy/ForumPics/DLC.gif

[ibsorgn]

You're confident you've correctly identified pin 1? can you tell if it has a yellow wire?


http://i90.photobucket.com/albums/k252/lnmccoy/ForumPics/DLC.gif


Top left for pin #1, used both Pins#4&5 for ground plus tried a chassis ground.

[ibsorgn]

You're confident you've correctly identified pin 1? can you tell if it has a yellow wire?


http://i90.photobucket.com/albums/k252/lnmccoy/ForumPics/DLC.gif

Are you a TT conversion using the same mix e.g. 1st gen ECU 2nd gen harness?

[RealMcCoy]

Top left for pin #1, used both Pins#4&5 for ground plus tried a chassis ground.

I would confirm the integrity of the yellow wire, as in that it is actually in pin 1, and going to the correct pin of the ECU... But it sounds like you either have a problem with the ECU or your meter has an unusual internal resistence and it isn't working for this task. Have you checked codes with it before? do you have access to any other 1st gen you could you could test it on?


Are you a TT conversion using the same mix e.g. 1st gen ECU 2nd gen harness?

No, why?

[ibsorgn]

I would confirm the integrity of the yellow wire, as in that it is actually in pin 1, and going to the correct pin of the ECU... But it sounds like you either have a problem with the ECU or your meter has an unusual internal resistence and it isn't working for this task. Have you checked codes with it before? do you have access to any other 1st gen you could you could test it on?



No, why?


OKay, I'll start from your first question, no yellow to pin#1
Best I could tell was Pin#1 pink, #2 open, #3 blue, #4 black, #5 black, #6 open #7 yellow, #8 yellow w/red stripe
Pin#9 open, #10 black maybe brown, #11 open, #12 yellow w/dark(maybe brown/black) stripe, #13 yellow w/dark (maybe brown/blue) stripe, #14 white w/red stripe, #15 open, #16 red

Colors to ECU - I don't know

ECU >>>. Not having any problems with it nor have I had any problems so I would guess the ECU is okay.

Multi meter, I have had it for a long time. Used it often. Put my entire race car and the 3000GT together with it, plus diagnosed many items with no apparent problems. I think it's okay.

Check codes with it? Narrow band O2, voltages and continuity on many things. Don't quite understand that question. (Voltage pulses - yes if that is what you mean)

No access to 1st gen vehicles, maybe the only one around that has one.

No, WHY - your response to I question as to whether you were a TT conversation person.
I want to know whether you are responding theoretically or through practical experience? I mean no disrespect as I appreciate your inputs.

[stealthee]

I will tell you that McCoy is the man when it comes to electrical. I'm a do-it-yourselfer and have taught myself a lot of stuff, but I can remember on more than one occasion having an electrical issue and McCoy was the one who had the answer.

[ibsorgn]

Great, hope he can figure this problem out. I have not read one post anywhere about pulling engine codes from a combination like mine and I know there are many 94/95 TT conversions out there but they are all staying very quiet in regards to this issue. I'll bet most have never pulled codes!

[RealMcCoy]

OKay, I'll start from your first question, no yellow to pin#1
Best I could tell was Pin#1 pink, #2 open, #3 blue, #4 black, #5 black, #6 open #7 yellow, #8 yellow w/red stripe
Pin#9 open, #10 black maybe brown, #11 open, #12 yellow w/dark(maybe brown/black) stripe, #13 yellow w/dark (maybe brown/blue) stripe, #14 white w/red stripe, #15 open, #16 red

Colors to ECU - I don't know


ECU >>>. Not having any problems with it nor have I had any problems so I would guess the ECU is okay.

Multi meter, I have had it for a long time. Used it often. Put my entire race car and the 3000GT together with it, plus diagnosed many items with no apparent problems. I think it's okay.

Check codes with it? Narrow band O2, voltages and continuity on many things. Don't quite understand that question. (Voltage pulses - yes if that is what you mean)

No access to 1st gen vehicles, maybe the only one around that has one.

No, WHY - your response to I question as to whether you were a TT conversation person.
I want to know whether you are responding theoretically or through practical experience? I mean no disrespect as I appreciate your inputs.

The multi-meter question was in reference to if you had ever pulled codes from a 1st gen with it...? I have no doubt that it works just fine, But the 1st gen ECU looks for a draw, (voltage drop) on that circuit to tell of it needs to output codes. If the meter has too much internal resistance (as is the case with most digital meters) the ECU won't know it's there... If it had been successfully used for this purpose in the past, we could rule out that possibility...

Most people that do a conversion install a TT engine harness... You don't have a lot of company in your situation. so I wouldn't expect a flood of experienced posters.

The issue here is you need to get your voltmeter hooked to pin 112 of the ECU... That is a yellow wire in both the 1st gen TT diagrams, and the diagrams for your car. What I did just find, is a discrepancy between the Mitchell diagrams and the FSM diagrams. It appears, (and seems to be backed up by your post) that the yellow wire to pin 112 of the ECU may actually terminate at pin 7 of the DLC... So you should try to hook your meter to that wire and see what happens...

[ibsorgn]

I'll give it a try tomorrow and if need be I'll get at the ECU and probe pin#112. One way or another I'll get that signal.

<<<<<<<<<<<<<<<<<<<<<<UPDATE>>>>>>>>>>>>>>>>>>>>>>>>>
Used Pin#7 and got two signals 11 and 39. Oh boy, just put in a new O2 sensor a while back. Spliting the single signal and feeding to both O2 pins. Wired in a couple of zener diodes to prevent signal feed back. BTW, ran for a year + with splitting the NA O2 sensor signal without a CEL. Question, if you might know, any difference in a O2 sensor for a Turbo vs a NA?

Fuel pump is new, new adjustable fuel regulator, don't believe I have any air leaks. Injectors were rebuilt about a year ago. All fuel components have less than 5k on them. So I'm guessing the O2 maybe causing the CEL.

P.S. Motor appears to be running fine and wide band shows AF normal.

Really appreciate the help Many THX

[ibsorgn]

The multi-meter question was in reference to if you had ever pulled codes from a 1st gen with it...? I have no doubt that it works just fine, But the 1st gen ECU looks for a draw, (voltage drop) on that circuit to tell of it needs to output codes. If the meter has too much internal resistance (as is the case with most digital meters) the ECU won't know it's there... If it had been successfully used for this purpose in the past, we could rule out that possibility...

Most people that do a conversion install a TT engine harness... You don't have a lot of company in your situation. so I wouldn't expect a flood of experienced posters.

The issue here is you need to get your voltmeter hooked to pin 112 of the ECU... That is a yellow wire in both the 1st gen TT diagrams, and the diagrams for your car. What I did just find, is a discrepancy between the Mitchell diagrams and the FSM diagrams. It appears, (and seems to be backed up by your post) that the yellow wire to pin 112 of the ECU may actually terminate at pin 7 of the DLC... So you should try to hook your meter to that wire and see what happens...

Used Pin#7 and got two signals 11 and 39. Oh boy, just put in a new O2 sensor a while back. Spliting the single signal and feeding to both O2 pins. Wired in a couple of zener diodes to prevent signal feed back. BTW, ran for a year + with splitting the NA O2 sensor signal without a CEL. Question, if you might know, any difference in a O2 sensor for a Turbo vs a NA?

Fuel pump is new, new adjustable fuel regulator, don't believe I have any air leaks. Injectors were rebuilt about a year ago. All fuel components have less than 5k on them. So I'm guessing the O2 maybe causing the CEL.

P.S. Motor appears to be running fine and wide band shows AF normal.

Really appreciate the help Many THX .........

[keo92stealth]

What year is the car? what part # ECU? have there been any wire harness changes?

changing wiring harnesses throws codes? will this also cause other sensors and thing to not work?

[RealMcCoy]

changing wiring harnesses throws codes? will this also cause other sensors and thing to not work?

How did you make that leap of logic...? I was simply asking the questions necessary in order to know which wire diagrams to look at...

[keo92stealth]

How did you make that leap of logic...? I was simply asking the questions necessary in order to know which wire diagrams to look at...

must have misunderstood you.

[ibsorgn]

changing wiring harnesses throws codes? will this also cause other sensors and thing to not work?

Anyone run a ECU/harness combination like mine?