I thought code 12 was the code for normal, than I read that is also means the distributor is not talking to the ecm.
The old ecm got toasted, I bought a used one plugged it in and I am now getting a code12. I thought I heard someone say the code 12 can also be caused by a faulty ecm. What I can do to check this. It's the only code I'm getting. The check engine light is on during normal operation. I don't know if the car starts cause it's on the batt. charger but I don't think it will. Thx.

Ben

 

Is there a procedure to check your ignition module?
My tach is acting funny too.

 

Ben:
Code twelve 3 times means everything is AOK!

 

Than why is my check engine light on all the time? It just stays on when the aldl connector isn't jumped. When I turn the key on, it flashes once, this means it sees the prom right? Then it just stays on. I jumped the aldl and it flashes the code 12 over and over, I counted at least 7 times.

Ben

 

It means that your computer has taken a long vacation from which it won't be returning and is waving "BYE BYE".
Actually it sounds like you may have a short or broken wire somewhere between the ECM and the ALDL. It will be the orange wire going from pin "BA8" of the ECM to pins "E" & "M" of the ALDL through pin "J" of connector C207.

 

i am in perpaetual awe at your knowledge of thirdgen wireing. were you on the design team or somthing?

 

He's the Trickster man, he knows all the tricks..

Would it be safe to assume the same thing if the SES light does not come on but you get code 12's over and over forever using the paperclip (but no codes using scantool)?

 

Which of your cars is doing this and does the CHECK ENGINE light come on when you turn the key to the "ON" position?

 

I checked for a short from either connector (aldl or ecm) and I check for continuity. Both were good. The batt. was dead, I charged it last night, started it this moring, let it warm up turn it off and now there is no check engine light. Don't know what it was, maybe the dead batt. had somethin to do with it. I was testing it with the charger power which was 13v.
Thx for your help anyway.

Ben

 

Its happening on my 89 IROC-Z (so 165 MAF TPI). I'm gonna go clear the codes and try again to make sure the Check Engine light is not coming on. I dont remember it coming on, but I want to double check. Thanks for the help Trickster.

 

Yes the SES comes on when the key is in the on position (but not started). Sounds like its time for a new ECM ...

 

Sounds more like you can relax if I am reading your posts correctly. The SES light is supposed to come on when you turn the key to the "ON" position and go off after you start the car. If there are no malfunctions in the car for which the computer throws a code then the computer will throw nothing but a code 12 at you over and over until the cows come home or Hawaii freezes over and the surfers take up ice fishing.

 

Oh, my bad then. I figgured this would be the perfect time to try the "going crazy" Smilie. Hahaha, looks more like an angry Smilie. Well, thanks for the good news Trickster. Really appreciate the help.