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.

Circuit/System Description

The head-up display (HUD) is a secondary display system capable of reflecting important vehicle information onto the windshield. The vehicle information is displayed using virtual imaging and is reflected off the windshield in front of the driver. Battery positive voltage is the power source to the HUD system. The HUD system can only be enabled when the ignition is active and in RUN position. The HUD receives vehicle information to be displayed via class 2 serial data circuit. The HUD also interfaces with the HUD switch via discreet circuits and the HUD switch inputs to the HUD is low.

Reference Information

Schematic Reference

Head Up Display Schematics

Connector End View Reference

    •  Displays and Gages Connector End Views
    •  Inline Harness Connector End Views

Description and Operation

Head Up Display (HUD) 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

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the head-up display (HUD).
  2. Test for less than 1.0 ohm of resistance between the ground circuit terminal 4 and ground.
  3. If greater than the specified value, test the HUD ground circuit for an open/high resistance.
  4. Verify a test lamp illuminates when connected between the battery positive voltage circuit terminal 6 and ground.
  5. If the test light does not illuminate, test the battery positive voltage circuit for an open/high resistance.
  6. If all circuits test normal, test or replace the HUD.

Repair Instructions

perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Control Module References for the HUD replacement, setup and programming
    •  Head Up Display Switch Replacement