GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2008 🢒 Cobalt 🢒 Engine 🢒 Engine Controls and Fuel - 2.0L 🢒 Malfunction Indicator Lamp (MIL) Diagnosis

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.

Circuit/System Description

Ignition voltage is supplied to the malfunction indicator lamp (MIL). The engine control module (ECM) turns the MIL ON by grounding the MIL control circuit.

Diagnostic Aids

If the condition is intermittent, move the related harnesses and connectors with the engine operating. Monitor the scan tool Circuit Test Status parameters for the component. The Circuit Test Status parameter will change from OK or Not run to Fault if there is a condition with the circuit or a connection.

Reference Information

Schematic Reference

    •  Instrument Cluster Schematics
    •  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

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 as commanded.
  2. 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 change from OK and Not Run or from Not Run and OK.
  3. 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. Ignition ON, verify that the instrument panel cluster (IPC) warning indicators are illuminated.
    2. ⇒If the IPC warning indicators are not illuminated, 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.
  2. Ignition OFF, disconnect the ECM X1 harness connector. Ignition ON, the MIL should not illuminate.
    3. ⇒If the MIL is illuminated, test the MIL control circuit terminal X1-54 for a short to ground. If the circuit tests normal, replace the IPC.
  3. Ignition ON, connect a 3A fused jumper wire between the MIL control circuit terminal X1-54 and ground. The MIL should illuminate.
    4. ⇒If the MIL does not illuminate, test the MIL control circuit for a short to voltage, or an open/high resistance. If the circuit tests normal, replace the IPC/bulb.
  4. If all circuits/connectors test normal, replace the ECM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Control Module References
    •  Instrument Cluster Replacement