Chart A-2, Wont Flash Code 12 Or Any Codes, Mil On Steady: Notes

Malfunction Indicator Light (MIL) will flash trouble codes when diagnostic request terminal in duty check data link connector is grounded. On vehicles with Federal emissions, MIL is also activated by a mileage switch at 50,000, 80,000 and 100,000 miles, alerting operator that vehicle is in need of regular maintenance service. Once service is performed, MIL cancel switch should be reset. Cancel switch is located behind instrument panel, attached to left speaker.

1. Checks for a short to ground in Purple/Yellow wire.
2. Checks for a faulty ECM or open in Blue/Yellow and Black wires to duty check data link connector.
3. Checks for short to ground in instrument panel printed circuit.
4. Checks to see if MIL cancel switch or mileage switch is faulty.