Testing Engine Control Module on K 1500 Truck 4WD V8-379 - Full Guide
ECM Diagnostic Chart
Test Description:
Numbers below refer to circled numbers on the diagnostic chart.
1. This step checks for short to battery voltage in wire to terminal "C" or faulty lamp driver. Normal voltage reading is 9-11 volts.
2. This step checks to see if problem is related to the ECM or the lamp driver. Normally, grounding terminal "C" should turn lamp "OFF". If it
does, the problem is related to the ECM and its wiring. If not, it is related to the lamp driver and its wiring.
3. Grounding terminal "A10" at ECM and finding light "ON", indicates an open in CKT 487 to terminal "C" of lamp driver. Normally, grounding
