Circuit/System Testing

Ignition OFF, exterior lamps OFF, disconnect the harness connector at the appropriate component listed below. It may take up to 2 min for all vehicle systems to power down.
- E5B Backup Lamp
- E83 Backup/Rear Fog Lamp
Test for less than 5 Ω between the ground circuit terminal 1 and ground.
- If 5 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 5 Ω
Connect a test lamp between the control circuit terminal 3 and ground, ignition ON.
Verify the test lamp turns ON and OFF when commanding the Backup 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.
  - X4 - (with T79)
  - X7 - (without T79)
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.
  - X4 - (with T79)
  - X7 - (without T79)
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 E Backup Lamp.