service engine

[Quacker]

Hi All
I picked up a 81 last week. The service engine light stays on all the time, the car seems to run OK but the light will not go off. I've disconnected the battery 4 times for over 15 min. to try and reset it. I also jumped pin D & E with a paper clip and it will not flash any kind of code like 12 for the self test, but just stays lit. Can this be a bad ECM ?

 

[Vader]

Turn off the ignition for at least 20 seconds. While monitoring the "SES" lamp, turn the ignition to RUN (do not crank the engine). Watch teh lamp closely on power-up. It should illuminate briefly, extinguish briefly, the illuminate and remain that way until the engine is started. YHou've already established that the lamp remains on after starting, but watch for the "lamp bounce" on power up just the same. It may be a hint to the problem.

Shorting the leftmost two pins of the ALDL invokes Field Service Mode. That should also be Pin E at the I/P connector and a good analog ground (Pin D).

Code #12: No Distributor Reference Pulse.
Code #13: Oxygen Sensor Circuit.
Code #14: Shorted Coolant Sensor Circuit.
Code #15: Open Coolant Sensor Circuit.
Code #21: Throttle Position Sensor Circuit.
Code #23: Mixture Control Solenoid Circuit.
Code #24: Vehicle Speed Sensor Circuit:
Code #32: Baro Sensor Circuit Low.
Code #34: Vacuum Map Sensor Circuit.
Code #42: EST Failure
Code #44: Oxygen Sensor Lean.
Code #45: Oxygen Sensor Rich.
Code #51: Faulty or Mis-Installed PROM
Code #52: Faulty ECM.
Code #53: Faulty ECM.
Code #54: Shorted Mixture Control Solenoid.
Code #55: Faulty Oxygen Sensor or ECM.

 

[Quacker]

Thank you Vader

As it turned out, I had to replace the ECM.

Thanks for your help.