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 X2 harness connector at the X50A fuse block - underhood.
Connect a test lamp between the control circuit terminal 18 and B+, vehicle in Service Mode.
Verify the test lamp turns ON and OFF when commanding the High Beams ON and OFF with a scan tool.
- If the test lamp is always OFF
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 control circuit terminal and ground.
  - If 1 V or greater, repair the short to voltage on the circuit.
  - If less than 1 V
3. Vehicle OFF.
4. 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 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.
2. Test for infinite resistance between the control circuit terminal and ground.
  - If less than infinite resistance, repair the short to ground on the circuit.
  - If infinite resistance, replace the K9 body control module.
- If the test lamp turns ON and OFF
Test or replace the X50A fuse block - underhood.