Circuit/System Testing
- Turn OFF the ignition.
- Disconnect the PCM.
- Turn ON the ignition with the engine OFF.
- If the MIL is still ON, test the MIL control circuit for a short to ground.
- If the MIL control circuit tested OK and the MIL stayed ON, replace the instrument cluster. Refer to Instrument Cluster Replacement .
- If the MIL control circuit tested OK and the MIL went out when the PCM was disconnected, replace the PCM. Refer to Control Module References .
- Measure for 12 volts from the MIL ignition voltage circuit in the instrument cluster harness connector to a ground.
- If there is less than 12 volts, test the MIL ignition voltage circuit for an open, or a short to ground, and an open fuse.
- Remove the fuse that supplies voltage to the MIL.
- Measure for less than 1 volt from the MIL control circuit in the PCM harness connector to a good ground.
- If there is more than 1 volt, test the MIL control circuit for a short to voltage.
- Install the fuse that supplies voltage to the MIL.
- The MIL should illuminate with a 3-amp fused jumper wire connected between the MIL control circuit in the PCM harness connector and a good ground.
- If the MIL does not illuminate, test the MIL control circuit for an open or high resistance.
- If the MIL control circuit tests OK, replace the instrument cluster. Refer to Instrument Cluster Replacement
- If the MIL does illuminate, but does not when commanded ON with a scan tool, replace the PCM. Refer to Control Module References .