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.

DTC Descriptor

DTC B3620: Head-Up Display (HUD) Information Up Switch

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

HUD Switch Signal Circuit

B3619

--

--

--

HUD Image Up Control Circuit

B3620

--

--

--

HUD Image Down Control Circuit

B3621

--

--

--

Illuminated Display Signal Circuit

B3634

--

--

--

Circuit/System Description

The head-up display (HUD) 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 up switch signal circuit in order to adjust image positions. When the HUD image up switch is depressed and the ignition is in the RUN position, the switch signal to the HUD is low.

Conditions for Running the DTC

The ignition is in RUN.

Conditions for Setting the DTC

The HUD detects that the HUD image up switch signal circuit is low for greater than 60 seconds.

Action Taken When the DTC Sets

The HUD ignores the malfunctioning switch circuit.

Conditions for Clearing the DTC

    • The DTC becomes history when the conditions for setting the DTC are no longer present.
    • The history DTC clears after 40 malfunction-free warm-up cycles.

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) switch.
  2. Ignition OFF, test for less than 1.0 ohm of resistance between the low reference circuit terminal 3 and ground.
  3. If greater than the specified value, test the low reference circuit for an open/high resistance.
  4. Ignition ON, test for 4.8 - 5.2 volts between the HUD image up control circuit terminal 7 and ground.
  5. If less than the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the HUD.
  6. If all circuits test normal, test or replace the 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