Circuit/System Testing

WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.

NOTE:

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

Ignition ON/Vehicle In Service Mode.
Verify the K124 Image Processing Module is not communicating.
- If the device is still communicating
1. Ignition/Vehicle OFF, disconnect all the harness connectors at the K124 Image Processing Module.
2. Ignition ON/Vehicle In Service Mode, refer to step 8 to diagnose a fault in the serial data circuits.
- Go to next step: If the device is not communicating
Ignition/Vehicle OFF, disconnect all the harness connectors at the K124 Image Processing Module.
Verify a test lamp illuminates between each of the ground circuit terminals and B+.
- If the test lamp does not illuminate
  Repair the open/high resistance in the ground circuit or ground connection.
- Go to next step: If the test lamp illuminates
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. Test for an open/high resistance in the B+ circuit.
  - If an open/high resistance is found, repair the fault in the circuit.
  - Go to next step: If an open/high resistance is not found
2. 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. Test for a short to ground in the B+ circuit.
  - If a short to ground is found, repair the fault in the circuit.
  - Go to next step: If a short to ground is not found
2. Replace the K124 Image Processing Module.
- Go to next step: If the test lamp illuminates
If equipped, verify a test lamp illuminates between each of the ignition circuit terminals, which has a fuse in the circuit, and ground.
- If the test lamp does not illuminate and the circuit fuse is good
1. Test for an open/high resistance in the ignition circuit.
  - If an open/high resistance is found, repair the fault in the circuit.
  - Go to next step: If an open/high resistance is not found
2. 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. Test for a short to ground in the ignition circuit.
  - If a short to ground is found, repair the fault in the circuit.
  - Go to next step: If a short to ground is not found
2. Replace the K124 Image Processing Module.
- Go to next step: If the test lamp illuminates
Test for less than 4.5 V between each of the Private Serial Data Active Safety CAN Bus Serial Data circuit terminals and ground.
- Circuit 8976
- Circuit 8977
- If 4.5 V or greater
  Repair the short to voltage in the serial data 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 greater than 100 Ω between each of the Private Serial Data Active Safety CAN Bus Serial Data circuit terminals and ground.
- Circuit 8976
- Circuit 8977
- If 100 Ω or less
  Repair the short to ground in the serial data circuit.
- Go to next step: If greater than 100 Ω
Test for 110 - 130 Ω between the pair of the Private Serial Data Active Safety CAN Bus Serial Data circuits.
- If less than 110 Ω
  Repair the short together between the serial data circuits.
- If greater than 130 Ω
  Repair the open/high resistance in the serial data circuit.
- Go to next step: If between 110 - 130 Ω
Inspect both harness and component connectors for contamination, corrosion, and terminal tension.
Reconnect the harness connectors at the K124 Image Processing Module.
Ignition ON/Vehicle In Service Mode.
Verify the DTC is not set again.
- If the DTC is set
  Replace the K124 Image Processing Module.
- Go to next step: If the DTC is not set
A fault is currently not present and may be an intermittent condition.