Circuit/System Testing

WARNING: This page is about a different car, the 2022 Cadillac CT5. However, it is still accessible from the selected car via links, so may be relevant.

NOTE:

Some control module ground circuits may require up to 20 min after the ignition is turned Off before achieving a resistance reading of less than 5 Ω. In most cases the readings will drop below 20 Ω within 1 min indicating the control modules are going to sleep.

Ignition and all accessories OFF.
Remove the KR124 Trailer Ignition Power Relay.
Verify a test lamp illuminates between ground circuit terminal 86 and B+.
- If the test lamp does not illuminate
  Repair the open/high resistance on circuit 2550 or the ground connection.
- Go to next step: If the test lamp illuminates
Ignition ON.
Verify a test lamp turns on between the control circuit terminal 85 and Ground.
- if the test lamp does not illuminate
1. Ignition Off.
2. Test the relay control circuit 5486 for a short to ground.
  - If a short to ground is found, repair the short to ground.
  - Go to next step: if a short to ground is not found
1. Test the relay control circuit 5486 for an open/high resistance concern.
  - if an open/high resistance is found repair the circuit.
  - Go to next step: if an open/high resistance is not found
2. Replace the K9 Body Control Module.
- Go to next step: If the test lamp illuminates.
Open the drivers door latch.
Cycle the Ignition On and Off.
Verify a test lamp turns On and Off the control circuit terminal 85 and Ground.
- If the test lamp is always On
1. Turn the Ignition Off.
2. Test control circuit 5486 for a short to voltage.
  - If a short to voltage is found repair short to voltage on the circuit.
  - Go to next step: if a short to voltage is not found
3. Replace the BCM.
- Go to next step: If the test lamp turns On and Off
Test or replace the KR124 Trailer Ignition Power Relay.