GM Service Manual Online
For 1990-2009 cars only

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 Descriptor

DTC P0650: Malfunction Indicator Lamp (MIL) Control Circuit

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

MIL Voltage Supply

P0650

P0650

--

--

MIL Control

P0650/MIL ON

P0650

P0650

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Circuit/System Description

Ignition 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.

Conditions for Running the DTC

    • The engine is operating.
    • Remote vehicle start, if equipped, is not active.
    • The ignition voltage is between 11-18 volts.
    • The DTCs runs continuously once the above conditions are met.

Conditions for Setting the DTC

The ECM detects that the commanded state of the driver and the actual state of the control circuit do not match for 5 seconds.

Action Taken When the DTC Sets

DTC P0650 is a Type B DTC.

Conditions for Clearing the DTC

DTC P0650 is a Type B DTC.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

  1. Ignition ON, command the MIL ON and OFF with a scan tool. The MIL should turn ON and OFF.
  2. Engine idling, command the MIL ON and OFF with a scan tool while observing the following control circuit status parameters:
  3. • MIL Ckt Short Gnd Test Status
    • MIL Ckt Open Test Status
    • MIL Ckt Short Volts Test Status
    • Each parameter should display OK or Not Run.
  4. 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

  1. If any other indicators are inoperative on the IPC, refer to Symptoms - Displays and Gages for further diagnosis.
  2. Ignition OFF, disconnect the ECM harness connector X1.
  3. Ignition ON, the MIL should not illuminate.
  4. If the MIL illuminates, test the MIL control circuit terminal 1-X1 for a short to ground. If the circuit test normal, replace the bulb/IPC.
  5. Ignition ON, connect a 3 A fused jumper wire between the MIL control circuit terminal 1-X1 and ground. The MIL should illuminate.
  6. If the MIL does not illuminate, test the MIL control circuit for a short to voltage or an open/high resistance. If the circuit test normal, replace the bulb/IPC.
  7. If all circuits test normal, replace the ECM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Instrument Cluster Bulb Replacement
    •  Control Module References for ECM replacement, setup, and programming