ecu will not connect!

[colt45 gto]

this 90 gto tt i got keeps throwing CEL now it could be knock sensor gone faulty, or its becuase its running too lean and causing knock, i tried to pull the codes but the obd port is dead ie even a test light will not light on it.

tried every scanner possible and too that connect flawlessly to 1st gens, the ecu has had caps but only the two big ones were replaced, the smaller one is original, i also noticed that they repaired a couple of circuit tracks with solder to the cap beside the small cap, so i'm wondering if thats the problem?

what i am going to do is see if my buddy has any ecu's left from when he used to break them, and buy one then send that to be capped and checked over by the ecu doctor over here.

it feels like its pulling hard then hits fuel cut, all vac pipes are on and in the correct places, the actuators are connected, stock boost solenoid is connected correctly. no after market boost controllers are fitted its totally stock.

i replaced the lambda sensor thinking it was the problem but its not, i did this because i cant connect to pull codes so i assumed that a faulty sensor would give wrong signals to the ecu. but its doing the same.

as far as i am aware the MAF is functioning i did not disconnect it yet to see if anything alters but until i can pull codes i cant pinpoint the problem.

has anyone got any idea how i can connect to pull codes? how about direct to the ecu incase whoever fitted the alarm cut the obd harness? any pins i can probe to pull codes direct for the ecu?

[blindmist]

I would first just try grounding pin 10 to ground and then turn the key over and see if the anti-lock light stays on.

[blindmist]

I would first just try grounding pin 10 to ground and then turn the key over and see if the anti-lock light stays on.

Have you tried this yet?

[colt45 gto]

haha i want to turn the CEL out not put another light on but yes i know what your getting at, if that doesn't work then they did chop the harness.

[blindmist]

haha i want to turn the CEL out not put another light on but yes i know what your getting at, if that doesn't work then they did chop the harness.

Yeah, if the light doesn't come on either the harness is cut or something is fucked up with the ecu. If you have another ECU to put in it, not even needing to start, but just to test the harness, then this would be good. I cannot imagine any reason as to why you would cut that harness but leave everything still there. .

[colt45 gto]

getting a fresh ecu tomorrow so hopefully all its ailments will be fixed.

[colt45 gto]

Thanks to Tony Hammett i now have a functioning ecu so now with that in the old one in the trunk as backup becuase i have not yet put new caps in (bad idea i know) new copper plugs, fresh oil all round, motor, tranny, T/Case and rear diff, coolant flushed with fresh antifreeze. just need to call and get some pipe to replace the brake booster pipe, and some small dry rotted vac lines. we are set for a nice 3500 mile round trip of europe

[colt45 gto]

grrrr!! still gettin random CEL and still the diagnostic port is dead or is it?

i'm wondering if its just a bit of bad connection causing the light to come on? but no one can say until i completely strip the dash out and fully check the wiring. i tried to pull codes direct from pin 113 on the ecu which is the diagnostic pin but nothing not even a bip or flash of the light on the tester.

if the ecu has no codes it would give some indication of a live circuit, like a alls well code. but i get zip diddly. i grounded the pin to put the srs light on and nothing, even with the fresh ecu.

i might just remove the damn bulb then i wont see nothing. but its awfull anoying i cant connect/communicate with the ecu to see whats up.

i have another idea i'm going to try tomorrow, connect the old ecu up leave it on the floor loose and wait for the light to come on then test direct off the ecu pin, see if i can get anything that way.

the light is so random it will come on while driving or sat idling in traffic. the engine tone does not change, there is no change in performance it simply lights the CEL sometimes a flash on then off sometimes its on for a few mins.sometimes it can be on for a full journey.

plugs are still white so its still lean as hell! they should be light brown in color.

maf is fine car runs lumpy with it disconnected. unless TPS is going bad?

[CoreyB]

I would suggest pulling the ecu out to the passenger floor and then pulling out the harness to it. Remove the cover and with the battery DISCONNECTED, start doing a ohm test from the back of the harness connector to the ECU's associated PCB link. I would tell you which wires went to the diagnostics port but I haven't really looked into it. Good luck bud.

[colt45 gto]

Have you tried this yet?

i have with no success mate. both ecu's althought pin 10 will probably go to the air bag ecu.

I would suggest pulling the ecu out to the passenger floor and then pulling out the harness to it. Remove the cover and with the battery DISCONNECTED, start doing a ohm test from the back of the harness connector to the ECU's associated PCB link. I would tell you which wires went to the diagnostics port but I haven't really looked into it. Good luck bud.

i'm wondering if it has no codes to throw it will not do anything? its been that long since i had to pull codes from one i simply cannot remember.
i can just picture the ecu looking at me like a cow looks at an oncoming train wondering wtf i'm doin?