Control Circuit Inspection

Ignition "OFF" and disconnect ECM connector.
Ignition "ON" & Engine "OFF".
Using a suitable wire, jumper the terminal 20 of ECM harness connector to chassis ground.
Is MIL bulb illuminated?
YES:
- Go to step 5.
NO:
- Remove instrument cluster and inspect MIL bulb. If it is burned out, replace bulb. If bulb is okay, locate source of open between bulb and (20/C133-4) or between bulb and Meter Fuse. Repair as necessary and go to "VERIFICATION OF VEHICLE REPAIR " procedure
Remove wire from ECM harness connector.
Does MIL bulb go out?
YES:
- Thoroughly check for loose, bent, or corroded terminals in MIL circuit (including circuit board). Repair as necessary and go to "VERIFICATION OF VEHICLE REPAIR " procedure.
NO:
- Check for source of short to GND between bulb and ECM (20/C133-4). Repair as necessary, and go to "VERIFICATION OF VEHICLE REPAIR " procedure