Wiring problems with computer

[jacek82]

My car keep buring out on the signal return on my computer. I'm up to my third computer. I have pulled out the complete engine harness and looked it completely over and found nothing.

The F'ed up part is the Cobra comp that I fixed signal return on board will run the car will run great but I have the rolling idle and a Code 67. \
The new A9L comp that I installed today. The board burn it self out right away. Which I'll fix tomorrow.

What am I over looking??

87 gt 5 speed converted (correct way matching T5 and Manuel 02 harness)

[liljoe07]

PIN 46 is obviously getting voltage. I would unplug the ECM, unplug the 8 pin connector for the 02's, unplug both switches on the Clutch pedal and the Tranny switchs. test for voltage at PIN 46 with key on, key on clutch down. And Cranking. then start to plug each connector back up one at a time and test again till you find the connector thats allowing voltage to PIN 46

[tmoss]

yep, you've got a conversion snafu....

There is a hardware difference between an auto processor & a manual processor. The difference is because of the way the NDS [neutral drive switch, manual transmission] & the NSS [neutral safety switch, auto transmission] are wired. They are both wired to the same pin#30 but the auto trans wiring grounds the pin to the starter solenoid & the manual grounds to signal return, during crank mode there is a voltage spike sent to pin-30 so the auto trans processor has a diode on pin 30 where as the manual processor doesn't, most of the time this won't cause a problem unless you get into a prolonged crank condition.

Those that want to convert their automatics to manuals, and swap the ECM, need to clip the wire going to pin 30 or else the ECM will fry the trace off the board. This leaves the manual EEC unable to dump codes, which looks for the loop through the neutral sensing switch of the T5 transmission.

Make sure you have a 5 speed O2 sensor harness when using an A9L or you will fry the trace also. The damage is common when people mismatch harnesses and use an automatic O2 sensor harness with an A9L computer.

[jacek82]

Originally Posted by tmoss

Those that want to convert their automatics to manuals, and swap the ECM, need to clip the wire going to pin 30 or else the ECM will fry the trace off the board. This leaves the manual EEC unable to dump codes, which looks for the loop through the neutral sensing switch of the T5 transmission.

Make sure you have a 5 speed O2 sensor harness when using an A9L or you will fry the trace also. The damage is common when people mismatch harnesses and use an automatic O2 sensor harness with an A9L computer.

The o2 harness I bought from fordfuelinjection.com so its the correct harness. And the five speed harness I pulled form a wrecked orginal five speed car.


So I have to cut the 30 pin wire only and my problems will be solved?

I remember reading that I have to ground it as well.

[tmoss]

don't cut anything until you know it's the problem - remove that pin from the connector and try it first.

These trace frying problems are almost definately related to wiring.

[jacek82]

I will be tracing the problem for sure. I do know for a fact that pin 30 has just under 5 volt going to it.

[liljoe07]

Originally Posted by jacek82

I will be tracing the problem for sure. I do know for a fact that pin 30 has just under 5 volt going to it.

Voltage Needs to monitored while cranking.

[jacek82]

QUOTE=liljoe07;8902683]Voltage Needs to monitored while cranking.[/QUOTE]
Pin30
With the iginiton off I have 0 volts, iginiton on 4.77 volts, crank spikes to 5.53 volts.

I pulled pin 30 out of the ecm block no volts any condition.

Also unhooked all the connection as suggusted before no difference.
Liljoe07


The voltage out put of the ecm is 4.8 with the pin 30 out.

[liljoe07]

Your measuring the wrong PIN. Measure PIN 46. Thats the SIGRTN wire. ECM unhooked right? Good! LOL

Check Voltage with Key off, Key on, Key on clutch down, and cranking.

What Tom is referring to is That on the Auto cars, PIN 30 is tied into PIN 46. So the Voltage at PIN 30 takes out The SIGRTN Curcuit(PIN 46). PIN 30 is gonna have voltage, its supposed to. But PIN 46 is not.

[jacek82]

liljoe
I ended up swaping wire on the o2 harness back to an auto. Also installed the A9P back in. Pin 46 has no voltage and Pin 30 had about 2.66

I was trying to set the car up to work on a 5 speed computer.

[liljoe07]

Originally Posted by jacek82

liljoe
I ended up swaping wire on the o2 harness back to an auto. Also installed the A9P back in. Pin 46 has no voltage and Pin 30 had about 2.66

I was trying to set the car up to work on a 5 speed computer.

Whatever gets you Car running.

[jacek82]

I agree. Thanks for your help any way.
Just would be nice to have the option of running koeo and koer test.

[liljoe07]

You cant run one now?

[jacek82]

I was under the impression that when you convert from a aod to a t5 out couldnt run koeo and koer test.

[liljoe07]

Plenty of Conversions Can run the KOEO and KOER tests. Code 67 will not allow a KOER test, but a KOEO test can be ran. So you saying you can run one now, or have you not tried it?

[jacek82]

I did do a koeo test with the cobra comp and got code 67 but never with the A9P comp.

Will have to try tomorrow.

[liljoe07]

The easy fix for code 67 is to ground PIN 30. This causes a permanent in neutral situation. And the KOER test should initiate.

[jacek82]

I'll run the tests tomorrow and see what happens. You're saying if I get a code 67 an the a9p comp I should be able to ground pin 30. Which will let me run a Koer test.

[liljoe07]

Originally Posted by jacek82

I'll run the tests tomorrow and see what happens. You're saying if I get a code 67 an the a9p comp I should be able to ground pin 30. Which will let me run a Koer test.

If the A9P Comp. is not showing a Code 67 dont worry about it.

[jacek82]

Well I tried to run both a KOEO and KOER test and got nothing. On the KOEO test the fuel pump turned on but the CEL did not turn on. The KOER test the car reved up and thats it.

[liljoe07]

Using a Scanner or test light?

Either way, run jumper from the STI to ground, use a test light hooked to the battery POS and STO terminal, Codes should flash

[jacek82]

Will give it a shot. Thanks again

[PurpleGT]

Ill have to subscribe as well. I too, do not have the ability to pull codes or even enter the self test mode currently with my new project car. Question without jacking your thread, is there a way to tell a auto o2 harness from a manual o2 harness? My car is a OG 5.0 car, but i think it may have been an auto at one time. Im about to go out and test some of the pins as stated here, and on fordfuelinjection's site, so hopefully this gets solved relatively easy. Is it easy to see the burnt trace in the computer?

[liljoe07]

Trace is pretty noticable. Try unhooking the 02 harness on at the 8 pin connector, then try and run the codes.

[keithnra]

Originally Posted by liljoe07

PIN 46 is obviously getting voltage. I would unplug the ECM, unplug the 8 pin connector for the 02's, unplug both switches on the Clutch pedal and the Tranny switchs. test for voltage at PIN 46 with key on, key on clutch down. And Cranking. then start to plug each connector back up one at a time and test again till you find the connector thats allowing voltage to PIN 46

this is what i was looki ng for

[Neomustangz]

Heres some pictures below on what to look for when looking at 02 harness's. I have gathered as much data as possible. I can confirm all these 02 harness' from their respectable cars from 87-93.

Lets look at the cannon plug first. Im going to label the 02 cannon plug from left to right from top to bottom. Holding the cannon plugs main clip portion at the 12 oclock position and the slots at the 4 and 9 oclock position. The top 4 pins are 1-4 and the bottom 4 pins are 5-8.


Notice the loop wire on the cannon plug on the below pictures. This loop is different than a 5 speed and AOD transmissions. The 02 harness's ARE different in those aspects. This is the culprit from the signal return trace being burned up. The loop wire we are focusing on are from a mass air 02 harness and or mass air engine harness from an 88-93 (87 is left out because there was not mass air then, and 88 only had california cars that were mass air with 8LD computers). Now sense 87 was left out ill also show a picture of the SPEED DENSITY 02 harness as well.

This is a picture of a speed density 02 harness. NOTICE There is NO loop wire.


This plug is from an AOD Transmission. From what i can tell. there is NO difference between an AOD mass air 02 harness from 88-93. They are all the same. Looking at the back of the cannon plug the wire is looped between pin number 5 and pin number 6


This is a plug from an 87-90 5 speed 02 harness. This pin is looped from pin 1 to pin 5.


And the last of the 02 harness loop wires are from 91-93 5 speed 02 harness's. Notice the loop wire from pin number 1 to pin number 6

[Neomustangz]

Also from a tuning standpoint for those with power adders. I have helped diagnosis problems at my local dyno shop for years of fox's. Wanted to mention people that run 87-88 cars that were naturally speed density cars that were still running original wiring and/or that have been either rewired to mass air or an engine harness swap. You will have to swap or repin your 02 harness as well along with the mass air harness as mention above. The software will have problems reading or talking to the 02's if you are going to chip the car on a custom tune. Its a nightmare for tuners and will run your dyno bill WAY up for the hours trying to figure it out.