For 1990-2009 cars

The head-up display (HUD) system has a motor driven cable-drive system 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. You may adjust the HUD image brightness by moving the HUD dim switch. The HUD up/down switch and the HUD dim switch are located within the HUD switch.

The HUD module uses various inputs in order to display the image. The vehicle speed is sent at 4000 pulses/mi from the powertrain control module (PCM). The HUD module also reduces the display image intensity whenever the park lights or the headlights are activated.

The HUD module performs a diagnostic system test (displays all of the segments) for 4 seconds whenever the ignition switch is turned to the RUN position.