Chart A-2, Won't Flash Code 12 Check Engine Light On Steadily: Notes

NOTE: Test numbers refer to test numbers on diagnostic chart.

If vehicle is equipped with Federal emissions, perform this step before going to next step.
If CHECK ENGINE light goes off when ECM is disconnected, circuit No. 419 is not shorted to ground.
This step checks for an open Blue/Yellow wire.
This has determined that CHECK ENGINE light circuit is okay and problem is caused by a faulty ECM.