GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2006 🢒 XLR 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 Head Up Display (HUD) Inoperative

Diagnostic Fault Information

Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

HUD Battery Voltage Circuit

--

2

--

--

HUD Ground Circuit

--

2

--

--

HUD Switch Ground Circuit

--

1

--

--

1. Head Up Display (HUD) Always ON

2. Head Up Display HUD Inoperative

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 main power source for the HUD system. However, the HUD system can only be enabled when the ignition is active and in the RUN position. The HUD system receives all vehicle information to be displayed via the class 2 serial data circuit. The HUD system interfaces with the HUD switch via discreet circuits. The HUD switch is a normally open switch and ground is provided from within the HUD switch when any switch press occurs.

Reference Information

Schematic Reference

    •  Head Up Display Schematics
    •  Interior Lights Dimming Schematics

Connector End View Reference

    •  Instrument Panel, Gages, and Console Connector End Views
    •  Lighting Systems Connector End Views

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. With the ignition ON, turn the HUD dimmer up switch to the full intensity.
    2. ⇒If the HUD display turns on normally, check for intermittent and poor connection at the harness connector of the HUD.
  2. With the ignition OFF, disconnect the HUD.
  3. Connect a test lamp between the HUD battery positive voltage and a good ground.
  4. Turn the ignition ON, with the engine OFF.
    5. ⇒If the test lamp does not illuminate, check the HUD battery positive voltage for an open or a high resistance.
  5. Connect a test lamp between the HUD battery positive voltage and the HUD ground circuit.
    6. ⇒If the test lamp does not illuminate, check the HUD ground circuit for an open or a high resistance.
  6. With the ignition turned OFF, disconnect the HUD switch.
  7. Connect a test lamp between the HUD switch ground circuit and the HUD battery positive voltage circuit.
  8. Turn the ignition ON, with the engine OFF.
    9. ⇒If the test lamp does not illuminate, check the HUD switch ground circuit for an open or a high resistance.
  9. Connect a test lamp between the HUD dimmer up switch signal circuit and the HUD battery positive voltage circuit while the HUD dimmer up switch is active.
  10. Turn the ignition ON, with the engine OFF.
    11. ⇒If the test lamp illuminates, replace the HUD.
    ⇒If the test lamp does not illuminate, test the HUD dimmer up switch signal circuit for an open or a high resistance.
    ⇒If the HUD dimmer up switch signal circuit tests normal, replace the HUD switch.

Repair Instructions

Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Head Up Display Switch Replacement .
    •  Control Module References for the instrument panel cluster (IPC) or HUD replacement, setup and programming