GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using the 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

The engine control module (ECM) determines when the engine oil should be changed and calculates the oil life in percent. The ECM sends this information via the serial data circuit to the instrument panel cluster (IPC) which displays the CHANGE ENGINE OIL indicator. The IPC displays the CHANGE ENGINE OIL indicator when the oil needs to be changed.

Reference Information

Schematic Reference

Instrument Cluster Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

    •  Indicator/Warning Message Description and Operation
    •  Instrument Cluster Description and Operation

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. Verify the scan tool Engine Oil Life Remaining parameter is greater than 5 percent.
  2. If lessthan 5 percent, reset the engine oil life.
  3. If the percent value is normal, replace the IPC.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  GM Oil Life System Resetting
    •  Control Module References for IPC replacement, setup, and programming