Circuit/System Testing

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.