The head-up display (HUD) is a secondary display system capable of reflecting important vehicle information on 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 power source to the HUD system. The HUD system can only be enabled when the ignition is active and in RUN position. The HUD receives vehicle information to be displayed via the serial data circuit. The HUD system also receives vehicle speed information via discreet vehicle speed signal circuit. The HUD interfaces with the HUD switch via discreet circuits and the HUD switch inputs to the HUD is low. The image down and image up switch are used to vertically adjust the HUD image on the windshield to accommodate various vehicle operator heights.The HUD dimming up switch initiates a smooth increase in the HUD display intensity until the switch is released or maximum intensity is achieved. The HUD does not have a separate Off switch. The HUD is turned off using the HUD dimming down switch. The HUD dimming down switch initiates a smooth decrease in the HUD intensity until the switch is released or the HUD is turned OFF.

Schematic Reference

Head Up Display Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Head Up Display (HUD) Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information.

1. Ignition ON, verify that when the HUD dimming up switch and the HUD dimming down switch are pressed, the HUD image intensity on the wind shield increases or decreases and the HUD scan tool Dimming level parameter displays a value between 2% and 98%.

⇒	If the Dimming Level parameter does not vary within the specified range, replace the HUD.

2. Ignition ON, verify that when the HUD switches are pressed and released , the HUD scan tool switch parameters toggle between Active and Inactive.

⇒	If the switch parameters do not toggle between Active and Inactive, refer to HUD Switch Malfunction.

HUD Inoperative

1. Ignition OFF, disconnect the harness connector at the HUD.
2. Ignition OFF, test for less than 5 ohms between the HUD ground circuit terminal 10 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance. If the circuit tests normal, replace the HUD.

3. Ignition ON, verify a test lamp illuminates when connected between the B+ circuit terminal 1 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the HUD.
4. Ignition ON, verify a test lamp illuminates when connected between the HUD image up switch signal circuit terminal 3 and B+ while pressing the HUD image up switch.

⇒	If the test lamp does not illuminate, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HUD switch.

5. Ignition ON, verify a test lamp illuminates when connected between the HUD image down switch signal circuit terminal 4 and B+ while pressing the HUD dimming down switch.

⇒	If the test lamp does not illuminate, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HUD switch.

6. If all circuits test normal, test or replace the HUD.

HUD Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the HUD switch.
2. Test for less than 5.0 ohms between the HUD switch ground circuit terminal 1 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, verify that all scan tool HUD Switch parameters are Inactive.

⇒	If any are not Inactive, test the signal circuit terminals listed below for a short to ground. If the circuit tests normal, replace the HUD.

•	HUD Image Up Switch Signal Circuit Terminal 2

•	HUD Image Down Switch Signal Circuit Terminal 3

4. Ignition ON, install a 3A fused jumper wire between the HUD switch signal circuit terminals listed below and the ground circuit terminal 1. Verify that all scan tool HUD switch parameters are Active.

•	HUD Image Up Switch Signal Circuit Terminal 2

•	HUD Image Down Switch Signal Circuit Terminal 3

⇒	If any are not Active, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HUD.

5. If all circuits test normal, test or replace the HUD switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.