Diagnostic Instructions
Circuit/System Description
Ignition 1 voltage is supplied directly to the malfunction indicator lamp (MIL). The powertrain control module (PCM) 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
When the ignition switch is ON and the engine is not running, the MIL is illuminated. Once the engine starts, the PCM turns the OFF the MIL. When an engine control system malfunction occurs, the PCM turns ON the MIL.
MIL Function
| • | The MIL informs the driver that a malfunction has been detected that requires service. |
| • | The MIL illuminates during a bulb test and a system test. |
| • | A diagnostic trouble code (DTC) will be stored if a MIL is requested by the PCM. |
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
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Ignition ON, the MIL should be illuminated.
- Operate the vehicle within the conditions that caused the concern.
Circuit/System Testing
Warning: Refer to Electric Coolant Fan Warning in the Preface section.
- Ignition ON, observe all the instrument panel cluster (IPC) indicators. The normal indicators should be illuminated.
- Ignition OFF, disconnect the X1 harness connector at the PCM.
- Ignition ON, connect a 3A fused jumper wire between the PCM MIL control circuit terminal X1-24 and ground. The MIL should illuminate.
| ⇒ | If the MIL does not illuminate, test the MIL control circuit for an open/high resistance. If the circuit tests normal, replace the IPC. |
| ⇒ | If the fuse opens, repair the MIL control circuit for a short to voltage. |
| ⇒ | If the MIL illuminates, replace the PCM. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
