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

Connector End View Reference

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

1. Turn ON the ignition, command the MIL ON and OFF with a scan tool. The MIL should turn ON and OFF when commanded.
2. If the vehicle passes the Circuit/System Verification Test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records List.

1. If any other IPC indicators or gages are inoperative, refer to Symptoms - Instrument Panel, Gages and Console .
2. Ignition OFF, disconnect the ECM harness connector.
3. Ignition ON, connect a 3-amp fused jumper wire between the MIL control circuit and the negative terminal of the battery. The MIL should illuminate.

⇒	If the MIL does not illuminate, test the MIL control circuit for a short to voltage, short to ground, or an open/high resistance. If the circuit test normal, replace the IPC/bulb.

⇒	If the MIL illuminates, inspect for a poor connection or replace the control module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.