Circuit/System Testing

WARNING: This page is about a different car, the 2017 Cadillac ATS. However, it is still accessible from the selected car via links, so may be relevant.

Ignition OFF.
Connect a test lamp between the trailer stop lamp control circuit (5188 BN/YE) at the W8 Blunt Cut Trailer Provision and ground, ignition ON.
Verify the test lamp turns ON and OFF when commanding the Trailer Brake Lamps ON and OFF with a scan tool.
- If the test lamp is always OFF
1. Ignition OFF, disconnect the X1 harness connector at the K68 Trailer Lighting Control Module.
2. Test for infinite resistance between the control circuit and ground.
  - If less than infinite resistance, repair the short to ground on the circuit.
  - If infinite resistance
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 K68 Trailer Lighting Control Module.
- If the test lamp is always ON
1. Ignition OFF, disconnect the X1 harness connector at the K68 Trailer Lighting Control Module, ignition ON.
2. Test for less than 1 V between the control circuit terminal and ground.
  - If 1 V or greater, repair the short to voltage on the circuit.
  - If less than 1 V, replace the K68 Trailer Lighting Control Module.
- If the test lamp turns ON and OFF
Test or replace the W8 Blunt Cut Trailer Provision.