Circuit/System Testing

WARNING: This page is about a different car, the 2016 GMC Acadia, 2016 Chevrolet Traverse, and 2016 Buick Enclave. However, it is still accessible from the selected car via links, so may be relevant.

NOTE:

All components may need to be disconnected on the cruise control brake signal circuit to isolate a short to voltage, short to ground or an open/high resistance condition. Use the schematic to identify the proper brake signal terminal (circuit 6311) at the K20 Engine Control Module.

Ignition/Vehicle Off, disconnect the harness connector at the K20 Engine Control Module, Ignition On/Vehicle in Service Mode.
Connect a test lamp between the signal circuit terminal and ground.
Verify the test lamp turns ON and OFF when pressing and releasing the brake pedal.
- If the test lamp is always OFF
1. Ignition/Vehicle Off, disconnect the harness connector at the K9 Body Control Module.
2. Test for infinite resistance between the signal circuit and ground.
  - If not infinite resistance, repair the short to ground on the circuit.
  - If infinite resistance.
3. Test for less than 2 Ω in the signal circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, replace the K9 Body Control Module.
- If the test lamp is always ON
1. Ignition/Vehicle Off, disconnect the harness connector at the K9 Body Control Module, Ignition On/Vehicle in Service Mode.
2. Test for less than 1 V between the signal circuit and ground.
  - If 1 V or greater, repair the short to voltage on the circuit.
  - If less than 1 V replace the K9 Body Control Module.
- If the test lamp turns ON and OFF
Replace the K20 Engine Control Module.