Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptors
DTC P1660: Malfunction Indicator Lamp (MIL) Control Circuit High VoltageDTC P1661: Malfunction Indicator Lamp (MIL) Control Circuit Low Voltage
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
MIL Voltage Supply | P1661 | P1661 | -- | -- |
MIL Control | P1661/MIL ON | P1661 | P1660 | -- |
Circuit/System Description
The malfunction indicator lamp (MIL) is located on the instrument panel cluster (IPC). The MIL informs the driver that an emission system fault has occurred and that the engine control system requires service. The control module monitors the MIL control circuit for conditions that are incorrect for the commanded states of the MIL.
Conditions for Running the DTC
| • | The ignition is ON or the engine is operating. |
| • | The DTCs runs continuously when the above conditions are met. |
Conditions for Setting the DTC
P1660
The engine control module (ECM) detects the MIL control circuit is shorted to voltage.
P1661
The ECM detects the MIL control circuit is open or shorted to ground.
Action Taken When the DTC Sets
DTC P1660 and P1661 are Type B DTCs.
Conditions for Clearing the DTC
DTC P1660 and P1661 are Type B DTCs.
Reference Information
Schematic Reference
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, command the MIL ON and OFF with a scan tool. The MIL should turn ON and OFF when commanded.
- Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
- If any other IPC indicators or gages are inoperative, refer to Symptoms - Displays and Gages.
- Ignition OFF, disconnect the harness connector at the ECM.
- Ignition ON, connect a 3A fused jumper wire between the MIL control circuit terminal 39 and ground. The MIL should illuminate.
| ⇒ | If the MIL does not illuminate, test the control circuit for a short to voltage, short to ground, or an open/high resistance. If the circuit tests normal, replace the IPC/bulb. |
| ⇒ | If the MIL illuminates, inspect for a poor connection or replace the ECM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for engine control module replacement, setup, and programming |
