Circuit Description
Battery positive voltage is supplied to the malfunction indicator lamp (MIL) through a logic module in the instrument panel cluster (IPC). The powertrain control module (PCM) turns the MIL ON by grounding the MIL control circuit.
MIL Function
| • | The MIL informs the driver that a malfunction has occurred and the vehicle should be taken in for service as soon as possible. |
| • | The MIL illuminates during a bulb test and a system test. |
| • | A DTC will be stored if a MIL is requested by the diagnostic. |
MIL Illumination
| • | The MIL will illuminate with the ignition switch ON and the engine not running. |
| • | The MIL will turn OFF when the engine is started. |
| • | The MIL will remain ON if the self-diagnostic system has detected a malfunction. |
| • | The MIL may turn OFF if the malfunction is no longer present. |
| • | If the MIL is illuminated and then the engine stalls, the MIL will remain illuminated as long as the ignition switch is ON. |
| • | If the MIL is not illuminated and the engine stalls, the MIL will not illuminate until the ignition switch is cycled OFF, then ON. |
Diagnostic Aids
If the problem is intermittent, refer to Intermittent Conditions .
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views | |||
1 | Did you perform the Diagnostic System Check-Engine Controls? | Go to Step 2 | |
Is the MIL illuminated? | Go to Step 3 | Go to Step 5 | |
3 | Test the MIL control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 6 | Go to Step 4 |
4 | Replace the instrument panel cluster (IPC). Refer to Instrument Cluster Replacement in Instrument Panel, Gages and Console. Did you complete the replacement? | Go to Step 6 | -- |
5 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | Go to Step 6 | -- |
6 |
Does the vehicle operate correctly without any unwanted MIL illumination, and without any stored DTCs? | System OK | |
