Hi all,

The check engine bulb was removed from the dash in my car, an 82 Firebird, 2.8L engine. I reconnected it the other day to see what would happen. The light remains on full time. I turned the key to the on position and shorted pins A and B on the aldl connector but the check engine light remained on. With the engine running I shorted Pins A and B again but the light still did not flash.

I have an 82 service manual and I see that on 82 in the ECU harness there is a remote lamp driver circuit. I checked that and all okay.
1) I shorted pins A and B on the aldl and checked I was getting a ground at the ECU, pin 5 on bigger ECU harness and I was.
2) Removed smaller ECU harness, turned ignition key to on and shorted pin G which supplies a Ground to the remote lamp driver to turn off check engine lamp. The lamp turned off.

So looks like I have a problem with the ECU. I have a dumb question but have to ask. Will the car run if the ECU is fried? I know that on start up the ECU doesn't control engine until it reaches certain temperature.

Thanks.

 

the car will run in limp home mode if the ecm fails ! Not sure how that works on a computer controlled carb. Those systems were junk using a mixture control solenoid.

 

Thanks for your reply. By limp mode would that be drives at 10 MPH all the way home or something. The car does seem to be running fine at the moment so the ECU must be doing something. It is probably the diagnostic circuitry that is fried. Can that be repaired or do I need to sourse a new ECU.

Wondered how the mixture control solenoid would work if the ECU was damaged but I don't think the ECU controls the Carb or the Distributor until the engine reaches a certain temperature . The Canadian Versions didn't use the M/C solenoid, weird!

 

The ecm has a limp home mode and has a basic calibration and will allow the car to run but not have any feedback form the oxygen sensor. I would be looking for a new ecm or do a non ccc carb swap or efi swap.

 

Probably the the easiest for me to do is get a new ECM for my current setup. I live in Ireland so difficult for me to sourse parts as all has to be imported from the US. I had a look round and there are some remanufactured ECM's from a company called Cardone. I presume all I need to do is swap over the Prom and hope for the best. A couple of second hand ones around but they might be no better than what I have.