Circuit/System Testing

Ignition OFF, disconnect the harness connector at the S27 Head-Up Display Switch.
Test for less than 30 Ω between the low reference circuit terminal 1 and ground.
- If 30 Ω or greater
1. Ignition OFF, disconnect the harness connector at the P29 Head-Up Display.
2. Test for less than 2 Ω in the low reference circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, replace the P29 Head-Up Display.
  - If less than 30 Ω
Ignition ON, connect the J-33431-C Instrument Panel Tester or a similar variable resistance tool between signal circuit terminal 6 and low reference terminal 1.
Verify the corresponding scan tool parameters change from Inactive to Active while creating the following resistance values:
- 604 Ω - Page Switch parameter
- 1624 Ω - Adjust Display Up Switch parameter
- 3534 Ω - Adjust Display Down Switch parameter
- If one or two of the scan tool parameters do not respond properly
  Replace the P29 Head-Up Display.
- If all the scan tool parameters respond properly
  Replace the P27 Head-Up Display Switch.
- If all the scan tool parameters do not respond properly
Ignition OFF. Disconnect the X1 harness connector at the P29 Head-Up Display.
Test for infinite resistance between the signal circuit terminal 6 and ground.
- If less than infinite resistance
  Repair the short to ground on the circuit.
- If infinite resistance
Test for less than 2 Ω in the signal circuit end to end.
- If 2 Ω or greater
  Repair the open/high resistance in the circuit.
- If less than 2 Ω
Ignition ON.
Test for less than 1 V between the signal circuit and ground.
- If 1 V or greater
  Repair the short to voltage on the circuit.
- If less than 1 V
If all circuits test normal, test or replace the P29 Head-Up Display.