Circuit/System Testing

WARNING: This page is about a different car, the 2012 Chevrolet Volt. However, it is still accessible from the selected car via links, so may be relevant.

Vehicle OFF, disconnect the X1 harness connector at the K20 engine control module.
Connect a test lamp between the signal circuit terminal 33 and ground, vehicle in Service Mode.
Verify the test lamp turns ON and OFF while pressing and releasing the brake pedal.
- If the test lamp is always OFF
1. Vehicle OFF, disconnect the X5 harness connector at the K9 body control module.
2. Test for infinite resistance between the signal 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 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. Vehicle OFF, disconnect the X5 harness connector at the K9 body control module, vehicle in Service Mode.
2. Test for less than 1 V between the signal circuit terminal 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.