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

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 MIL lamp must be commanded ON.
    • DTC P0650 runs continuously when the ignition is ON.

Conditions for Setting the DTC

The control module detects that the commanded state of the MIL driver and the actual state of the control circuit do not match for more than 3 seconds.

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
    •  Instrument Cluster Schematics

Connector End View Reference

    •  Engine Control Module Connector End Views
    •  Engine Controls Connector End Views
    •  Engine Controls Component Views
    •  Instrument Panel, Gages, and Console Component Views
    •  Instrument Panel, Gages, and Console 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
    •  Diagnostic Trouble Code (DTC) Types

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions
    •  Scan Tool Output Controls

Diagnostic Aids

An intermittent or poor connection at the MIL control circuit in the inline harness connector may cause this DTC to set. Inspect the connector terminals for any condition that may result in excessive resistance. Refer to Testing for Intermittent Conditions and Poor Connections .

Circuit/System Verification

  1. Ignition ON, the MIL should turn ON and OFF when commanded with a scan tool.
  2. Engine running, observe the DTC information with a scan tool. DTC P0650 should not set.
  3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame Records data.

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