Circuit/System Testing

NOTE:

Each component with backlighting may need to be disconnected to isolate a short to voltage or short to ground. Use the wiring schematics to identify the following:

Backlighting components the vehicle is equipped with
Each component's control and ground circuit terminals
Component locations on the backlighting 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 F26UA fuse at the X50A Fuse Block - Underhood.
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 F26UA fuse at the X50A Fuse Block - Underhood.
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 component with inoperative dome/courtesy lamp. It may take up to 2 min for all vehicle systems to power down.
Test for less than 10 Ω between the appropriate ground circuit terminal listed below and ground.
- E8A Door Sill Plate Lamp - Driver terminal 2 (with B7G)
- E8B Door Sill Plate Lamp - Passenger terminal 2 (with B7G)
- E8J Instrument Panel Courtesy Lamp - Left terminal 2
- E8K Instrument Panel Courtesy Lamp - Right terminal 2
- E37LF Dome/Reading Lamps - Left Front terminal 4
- E37RF Dome/Reading Lamps - Right Front terminal 4
- 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.
- E8A Door Sill Plate Lamp - Driver terminal 1 (with B7G)
- E8B Door Sill Plate Lamp - Passenger terminal 1 (with B7G)
- E8J Instrument Panel Courtesy Lamp - Left terminal 1
- E8K Instrument Panel Courtesy Lamp - Right terminal 1
- E37LF Dome/Reading Lamps - Left Front terminal 3
- E37RF Dome/Reading Lamps - Right Front terminal 3
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 appropriate harness connector listed below at the K9 Body Control Module.
  - X2
  - X7
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 appropriate harness connector listed below at the K9 Body Control Module, ignition ON.
  - X2
  - X7
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 dome/courtesy lamp.