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.

Ignition OFF and all vehicle systems OFF. Disconnect the X5 harness connector at the K9 Body Control Module, ignition ON.
Verify the P12A Horn - High Note and P12B Horn - Low Note are not activated.
- If the P12A Horn - High Note and P12B Horn - Low Note are activated
1. Ignition OFF, disconnect the X1 harness connector at the X50A Engine Wiring Harness Junction Block.
2. Test for infinite resistance between the K9 Body Control Module control circuit terminal 11 X5 and ground.
  - If less than Infinite resistance, repair the short to ground on the circuit.
  - If infinite resistance, test or replace the X50A Engine Wiring Harness Junction Block.
- Go to next step: If the P12A Horn - High Note and P12B Horn - Low Note are not activated
Connect a 3 A fused jumper wire between the control circuit terminal 11 X5 and ground.
Verify the P12A Horn - High Note and P12B Horn - Low Note are activated.
- If the P12A Horn - High Note and P12B Horn - Low Note do not activate
1. Ignition OFF, remove the jumper wire, disconnect the X1 harness connector at the X50A Engine Wiring Harness Junction Block, ignition ON.
2. Test for less than 1 V between the K9 Body Control Module control circuit terminal 11 X5 and ground.
  - If 1 V or greater, repair the short to voltage on the circuit.
  - Go to next step: If less than 1 V
3. Test for less than 2 Ω in the control circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, replace the X50A Engine Wiring Harness Junction Block.
- Go to next step: If the P12A Horn - High Note and P12B Horn - Low Note activates
Replace the K9 Body Control Module.