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.

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.

DTC P1660 and P1661 are Type B DTCs.

DTC P1660 and P1661 are Type B DTCs.

Schematic Reference

Engine Controls Schematics

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, command the MIL ON and OFF with a scan tool. The MIL should turn ON and OFF when commanded.
2. 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.

1. If any other IPC indicators or gages are inoperative, refer to Symptoms - Displays and Gages.
2. Ignition OFF, disconnect the harness connector at the ECM.
3. 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.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.