Circuit/System Testing

WARNING: This page is about a different car, the 2021 Buick Enclave. However, it is still accessible from the selected car via links, so may be relevant.

NOTE:

Each lighting component may need to be disconnected to isolate a short to ground. Use the schematics to identify the following:

Lighting components the vehicle is equipped with
Each component's control and ground circuit terminals
Component locations on the lighting control circuit

Ignition OFF, disconnect the X1 harness connector at the K9 Body Control Module, ignition ON.
Verify a test lamp illuminates between the B+ circuit terminal 4 and ground.
- If the test lamp does not illuminate and the circuit fuse is good
1. Ignition OFF, remove the fuse at the X51A Fuse Block - Instrument Panel.
2. Test for less than 2 Ω in the B+ circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
- If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF, remove the fuse at the X51A Fuse Block - Instrument Panel.
2. Test for infinite resistance between the B+ circuit and ground.
  - If less than infinite resistance, repair the short to ground on the circuit.
  - If infinite resistance, replace the K9 Body Control Module.
- Go to next step: If the test lamp illuminates
Ignition OFF, connect the X1 harness connector at the K9 Body Control Module.
Ignition OFF, scan tool disconnected, all doors closed, all accessories OFF, open and close drivers door, disconnect the harness connector at the inoperative component listed below. It may take up to 2 min for all vehicle systems to power down.
- E8D Door Courtesy Lamp - Driver
- E8P Door Courtesy Lamp - Passenger
- A98 Front Overhead Console Assembly
- E37M Dome/Reading Lamps - Middle
- E37R Dome/Reading Lamps - Rear
- E28 Center Console Compartment Lamp
Test for less than 10 Ω between the appropriate ground circuit terminal listed below and ground.
- E8D Door Courtesy Lamp - Driver terminal 2
- E8P Door Courtesy Lamp - Passenger terminal 2
- A98 Front Overhead Console Assembly terminal 5
- E37M Dome/Reading Lamps - Middle terminal 3
- E37R Dome/Reading Lamps - Rear terminal 3
- E28 Center Console Compartment Lamp terminal 2
- If 10 Ω or greater
1. Ignition OFF.
2. Test for less than 2 Ω in the ground circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, repair the open/high resistance in the ground connection.
- Go to next step: If less than 10 Ω
Connect a test lamp between the appropriate control circuit terminal listed below and ground, ignition ON.
- E8D Door Courtesy Lamp - Driver terminal 1
- E8P Door Courtesy Lamp - Passenger terminal 1
- A98 Front Overhead Console Assembly terminal 8
- E37M Dome/Reading Lamps - Middle terminal 2
- E37R Dome/Reading Lamps - Rear terminal 2
- E28 Center Console Compartment Lamp terminal 1
Verify the test lamp turns ON and OFF when commanding the Courtesy Lamps ON and OFF with a scan tool.
- If the test lamp is always OFF
1. Ignition OFF, disconnect the X7 harness connector at the K9 Body 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.
  - Go to next step: 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 K9 Body Control Module.
- If the test lamp is always ON
1. Ignition OFF, disconnect the X7 harness connector at the K9 Body 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 K9 Body Control Module.
- Go to next step: If the test lamp turns ON and OFF
Test or replace the inoperative dome lamp.