Chart A6 - Won't Flash Code 12
NOTE:
The following step numbers refer to the numbers in the accompanying flow chart(s).
- This step checks for short to battery voltage in wire to terminal "C" or faulty light driver. Normal reading is 9 to 11 volts.
- This step checks to see if problem is related to the ECM or light driver. Grounding terminal "C" should turn light off.
- Grounding terminal "G" at ECM and finding light on indicates an open in wire to terminal "C" of light driver. Grounding terminal "G" should turn light off.
- This step checks for open in wire from ECM to test terminal in ALCL connector. The light should flash Code 12 when terminal "5" is grounded.
- This checks for proper voltage supply to ECM. Both should read over 9 volts. Term. "C" is ignition and terminal "R" is constant battery voltage for long term memory.
- This test checks for bad ground in ECM. Terminals "A" and "U" are connected together inside ECM.
- This step distinguishes between a faulty ECM and PROM. Normal response is for Code 51 to flash even though PROM is not installed in ECM. If no Code 51, ECM is faulty.
NOTE:
Check fuses that supply power to ECM. Repeat Diagnostic Circuit Check after any repair.