Circuit/System Testing

NOTE:

Use the schematics and connector end views to identify the control module's ground, B+, ignition, and Ethernet serial data circuit terminals.

Ignition/Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. Disconnect the harness connectors at the P29 Head-Up Display. It may take up to 10 min for all vehicle systems to power down.
Test for less than 10 Ω between each of the ground circuit terminals and ground.
- If 10 Ω or greater
1. Ignition/Vehicle OFF.
2. Test for less than 2 Ω in the ground circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, repair the open/high resistance in the ground connection.
- Go to next step: If less than 10 Ω
Ignition ON/Vehicle In Service Mode.
If equipped, verify a test lamp illuminates between each of the B+ circuit terminals and ground.
- If the test lamp does not illuminate and the circuit fuse is good
1. Ignition/Vehicle OFF, remove the test lamp.
2. Test for less than 2 Ω in the B+ circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
- If the test lamp does not illuminate and the circuit fuse is open
1. Ignition/Vehicle OFF, remove the test lamp.
2. Test for infinite resistance between the B+ circuit and ground.
  - If less than infinite resistance, repair the short to ground on the circuit.
  - If infinite resistance, replace the P29 Head-Up Display.
- Go to next step: If the test lamp illuminates
If equipped, verify a test lamp illuminates between each of the ignition circuit terminals and ground.
- If the test lamp does not illuminate and the circuit fuse is good
1. Ignition/Vehicle OFF, remove the test lamp.
2. Test for less than 2 Ω in the ignition circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, verify the fuse is OK and there is voltage at the fuse.
- If the test lamp does not illuminate and the circuit fuse is open
1. Ignition/Vehicle OFF, remove the test lamp.
2. Test for infinite resistance between the ignition circuit and ground.
  - If less than infinite resistance, repair the short to ground on the circuit.
  - If infinite resistance, replace the P29 Head-Up Display.
- Go to next step: If the test lamp illuminates
Ignition/Vehicle OFF, disconnect the harness connectors at the A11 Radio.
Ignition ON/Vehicle In Service Mode.
Test for less than 4.5 V between each of the Ethernet serial data circuit terminals and ground.
- If 4.5 V or greater
  Repair the short to voltage in the circuit.
- Go to next step: If less than 4.5 V
Ignition/Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 10 min for all vehicle systems to power down.
Test for infinite resistance between each of the Ethernet serial data circuit terminals and ground.
- If less than infinite resistance
  Repair the short to ground in the circuit.
- Go to next step: If infinite resistance
Test for infinite resistance between the pair of Ethernet serial data circuit terminals.
- If less than infinite resistance
  Repair the short together in the circuits.
- Go to next step: If infinite resistance
Test for less than 2 Ω in each of the Ethernet serial data circuits end to end.
- If 2 Ω or greater
  Repair the open/high resistance in the circuit.
- Go to next step: If less than 2 Ω
Replace the P29 Head-Up Display.
Ignition/Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 10 min for all vehicle systems to power down.
Ignition ON/Vehicle In Service Mode.
Verify DTC U190B does not set.
- If the DTC sets
  Replace the A11 Radio.
- Go to next step: If the DTC does not set
All OK.