GM Service Manual Online
For 1990-2009 cars only

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Circuit/System Description

The powertrain control module (PCM) / engine control module (ECM) monitors the cruise control switch. When the cruise on/off switch is switched ON, the cruise control switch is closed and the signal circuit is high. When the cruise on/off switch is switched OFF, the cruise control switch is open and the signal circuit is low.

Reference Information

Schematic Reference

Cruise Control Schematics

Connector End View Reference

    •  Powertrain Control Module Connector End Views (4.2L)
    •  Engine Control Module Connector End Views (non 4.2L)

Description and Operation

Cruise Control Description and Operation

Electrical Information Reference

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

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions

Circuit/System Verification

Important: Vehicles without a driver information center (DIC) do not have a cruise control indicator in the instrument panel cluster (IPC). Do not perform this diagnostic if the vehicle does not have a DIC.

  1. Ignition ON, install a scan tool and command the Cruise Control Lamp Test ON. Verify that the cruise control indicator in the IPC is illuminated.
  2. If the indicator is not illuminated, replace the IPC.
  3. If all circuits test normal, replace the ECM / PCM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for PCM (4.2L) / ECM (non 4.2L) or IPC replacement, setup, and programming.