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 provide an overview of each diagnostic category.

DTC Descriptor

DTC P0650: Malfunction Indicator Lamp (MIL) Control Circuit

Diagnostic Fault Information

Circuit

Short to Ground

Open

Short to Voltage

MIL Voltage Supply

P0650

P0650

--

MIL Control

P0650

P0650

P0650

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 engine control module (ECM) performs a self test for the MIL lamp and its circuitry by commanding the MIL ON and OFF every time the engine is started. The ECM 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.
    • Battery voltage is between 10-16 V.

Conditions for Setting the DTC

    • MIL control command is ON.
    • Low voltage condition on the MIL control circuit when the indicator is commanded OFF for longer than 1 second.
        OR
    • MIL control command is OFF.
    • High voltage condition on the MIL control circuit when the indicator is commanded ON for longer than 1 second.

Action Taken When the DTC Sets

DTC P0650 is a Type B DTC.

Conditions for Clearing the MIL/DTC

DTC P0650 is a Type B DTC.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Engine Controls Component Views
    •  Engine Control Module 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

    •  Scan Tool Data List
    •  Scan Tool Data Definitions

Circuit/System Verification

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

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the IPC.
  2. Ignition ON, verify that a test lamp illuminates between the ignition circuit and ground.
  3. If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, replace the IPC.
  4. Connect a test lamp between the control circuit and the ignition circuit.
  5. Command the MIL ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
  6. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.
    If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
  7. If all circuits test normal, replace the IPC.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM and IPC replacement, setup, and programming