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 head-up display (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 a dimming switch which gives the driver the ability to adjust the brightness of the HUD. The CHECK GAGES indicator illuminates for 3 seconds during the displays test.

The HUD displays the following:

    • The check gages indicator
    • The high beam indicator
    • The km/h and MPH indicators
    • The speedometer reading
    • The turn signal indicators

Speedometer

The HUD displays the vehicle speed based on information from the PCM. The PCM converts the data from the vehicle speed sensor to a 4000 pulses/mile signal. The HUD uses the vehicle speed signal circuit (4000 pulses/mile) from the PCM in order to calculate the vehicle speed. The speedometer defaults to 0 mph (0 km/h) if a malfunction in the vehicle speed sensor signal circuit exists. The speedometer displays either miles or kilometers as requested by the activation of the Eng/Met button on the DIC. The associated indicator illuminates.

CHECK GAGES Inputs

The IPC monitors different inputs and vehicle messages and sends the information to the HUD. The CHECK GAGES indicator illuminates when the HUD receives this specific information:

    • The ABS indicator is illuminated
    • The air bag indicator is illuminated
    • The battery indicator is illuminated
    • The BRAKE indicator is illuminated (the vehicle is driven more than 20 feet (6.1 meters) with the park brake applied)
    • The BRAKE indicator is illuminated (low brake fluid)
    • The COOLANT indicator is illuminated
    • The Door Ajar indicator is illuminated (the vehicle is driven more than 20 feet with the door ajar signal active)
    • The Low Fuel indicator is illuminated
    • The MIL indicator is illuminated
    • The oil pressure indicator is illuminated
    • The TRAC OFF indicator is illuminated
    • The Trunk Ajar indicator is illuminated (the vehicle is driven more than 20 feet with the trunk ajar signal active)

The CHECK GAGES indicator illuminates for 3 seconds during the displays test.

English/Metric Input

The HUD displays the speedometer in either English (mph) units or metric (km/h) units based on a hardwire input from the IPC. The units are changed when the DIC Eng/Met button is pressed.