Hello All:

I have a shop manual and experience with a 1987 Vin H Firebird Formula.

I'm working on a 1982 Trans-Am, and I noticed that it did not appear to go into
"field service mode" where the SES light is supposed to flash every few seconds to indicate lean/rich and closed or open loop while the diagnostic terminal is grounded while the car is running.

Can anyone tell me if a 1982 ECM should do the same thing and if so offer any theories you might have as to why the SES light does not flash.

Prior to running into the problem with the SES light, which is the subject of another post, the SES was flashing code 12 with the diagnostic terminal grounded with the car not running...

Thanks for any help!

Lee B.

 

Code 12 means there are no codes. Its just a standard code to let you know the ecm is responding as it should.

 

Well since you have mentioned running the car with the ALDL grounded. You should not be running the car with the ALDL grounded unless you are using a scan tool, otherwise you run the risk of frieing the ECM by doing this. I don't know if your shop manual is also for a 1987, but there is a big difference in the wiring and computers between 1982 & 1987. Might explain why your SES light doesn't work and the computer won't talk to a scan tool that you mentioned in your other thread.

 

Trickster:

Thanks very much for the input. It's helpful to know theres a lot of differences between the 82 and 87 computers, and to NOT short the diagnostic connection to ground with the car running.

I was able to get a new "light control module" in ONE day from the dealer. (A miracle, LOL). All it is is a tiny board with 3 resistors, 1 transistor to switch on the light, a diode and a capacitor.

It cost $30! Oh well, thats about right for a dealer part.

It had an extra pin on it, so I had to pull a blue unlocking thing off the socket it goes to, and then a black pin thing that would have stopped it from being able to plug in.

I pluged it in and, viola! Light is working and ECM flashes code 12 again!

Thank ***!

Lee B.

Maybe this can help someone else...

 

87 was a TBI year for some engines but not all, some in firebirds camaros were still carb even in 87 88 maybe 89 too,

and beginning in 85 there was MPFI but i dont know if just for v-6 engines, or if was on some v-8 engines also,

i removed the entire ECM and its harness from the 82 t/a LG4 car, the harness is the big one by itself in a plastic ribbed loom on pass side going down into firewall behind the fender, its real easy to snake out of there and remove,
its for all the sensors and the carb and the HEI for 80-up mainly 305 engines, 4bbl aluminum intake, LG4, L69, etc.,


good luck