GM Service Manual Online
For 1990-2009 cars only

The head-up display (HUD) is a secondary display system that optically projects critical vehicle information onto the windshield. The HUD system has an electric tilt adjust that is controlled by the HUD up/down switch. Moving this switch directs the motor to move the HUD image up or down on the windshield. The HUD is also equipped with automatic dimming which gives the HUD the ability to sense outside light conditions, via a photo-cell and automatically adjusts the brightness levels. You may manually adjust the HUD image brightness by moving the HUD dim switch.

The HUD displays the following images:

    • The speedometer reading (speed up to 120 mph)
    • The turn signal indicators
    • The high beam indicator
    • The low fuel indicator
    • The check gages indicator
    • The radio frequency, including AM, FM, CD, and Tape
    • Backup vehicle speed
    • Values in English or metric units

Speedometer

The speedometer is shown on the head-up display (HUD) as a 3-digit display. The HUD speedometer is capable of displaying up to 120 mph. The HUD receives a serial data message from the engine control module (ECM) or the powertrain control module (PCM) indicating vehicle speed. If the serial data message from the ECM/PCM is invalid the HUD will use the serial data message from the electronic brake control module (EBCM) instead.

LH Turn Signal and RH Turn Signal Indicators

The head-up display (HUD) receives a serial data message from the body control module (BCM) that the turn signals have been requested.

High Beam Indicator Input

The head-up display (HUD) receives a serial data message from the body control module (BCM) that the high beams have been requested.

Low Fuel

The head-up display (HUD) receives a serial data message from the (IPC) indicating low fuel.

CHECK GAGES

The instrument panel cluster (IPC) monitors different inputs and vehicle messages and sends the information to the head-up display (HUD) via a serial data message. The HUD illuminates the CHECK GAGES indicator when it receives certain information from the IPC.

The HUD will illuminate the Check Gages indicator for the following messages:

    • Brake failure
    • Charging system/generator fault
    • Coolant temp hot
    • Low brake fluid level
    • Low oil pressure
    • Low tire pressure
    • Parking brake
    • Voltage

Radio

    • The head-up display (HUD) displays the following radio information depending on the current radio settings:
       - Frequency
       - Band
       - CD Track #
       - Current Disk # (for multiple disk player)
       - Cassette icon (when cassette is playing)
       - MP3 (folder name and track #)
       - Rear Seat Entertainment (RSE) (ON/OFF)
    • When the radio station, CD, or cassette are changed, the HUD displays the new information for 5 seconds.
    • The HUD receives a serial data message indicating a change in the setting from the radio.
    • The HUD image blanks when the radio is seeking or scanning.

Navigation

The navigation system displays the following information:

    • The direction/maneuver arrow and destinations symbols
    • Arbitrary text for directions
    • The distance to next maneuver
    • The distance count down bar
    • The compass heading

Backup Vehicle Speed

The head-up display (HUD) receives a serial data message from the body control module (BCM) indicating the backup vehicle speed.

HUD English/Metric

The head-up display (HUD) illuminates the speedometer in either english (mph) or metric (km/h) units depending upon the serial data message received from the instrument panel cluster (IPC).