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.

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

HUD Image Down Switch Signal Circuit

HUD Image Up Switch Signal Circuit

1

1

--

HUD Switch Ground Circuit

--

1

--

1. Head Up Display Image Adjustment Inoperative

Circuit/System Description

The head-up display (HUD) image down or image up switch is used to vertically adjust the HUD image on the windshield to accommodate various vehicle operator heights. The HUD monitors the image down or image up switch signal circuit in order to adjust image positions. When the HUD image down or image up switch is depressed and the ignition is in the RUN position, the switch signal to the HUD is low.

Reference Information

Schematic Reference

    •  Head Up Display Schematics
    •  Interior Lights Dimming 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 dimming/head-up display (HUD) switch.
  2. Test for less than 1 ohm of resistance between the HUD switch ground circuit terminal 1 and ground.
  3. If greater than 1 ohm, test the ground circuit for an open/high resistance.
  4. Ignition ON, verify the scan tool Adjust Display Down Switch or the Adjust Display Up Switch parameter is Inactive.
  5. If any is not Inactive, test the appropriate image switch signal circuit terminals 2 or 3 for a short to ground. If the circuit(s) tests normal, replace the HUD.
  6. Install a 3A fused jumper wire between the image down switch signal circuit terminal 3 or the image up switch signal circuit terminal 2 and the ground circuit terminal 1. Verify the scan tool Adjust Display Down Switch or Adjust Display Up Switch parameter is Active.
  7. If any is not Active, test the appropriate image switch signal circuit terminals 2 or 3 for a short to voltage or an open/high resistance. If the circuit(s) tests normal, replace the HUD.
  8. If all circuits test normal, test or replace the dimmer/HUD switch.

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