Diagnostic Instructions
Circuit/System Description
Ignition 1 voltage is supplied directly to the malfunction indicator lamp (MIL). The engine control module (ECM) turns the MIL ON by grounding the MIL control circuit. There should be a steady MIL with the ignition ON and the engine OFF.
MIL Operation
The MIL is located on the instrument panel (I/P).
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. |
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Component Connector End Views
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the ECM.
- Ignition ON, observe the malfunction indicator lamp (MIL).
| ⇒ | If the MIL is illuminated, test the control circuit for a short to ground between the ECM and the I/P. If the circuit tests normal, replace the I/P or the DIC/clock. |
| ⇒ | If the MIL is not illuminated, replace the ECM. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
