Circuit/System Testing

Ignition OFF, exterior lamps OFF, disconnect the harness connector at the appropriate E42 Tail Lamp Assembly.
Test for less than 15 Ω between the ground circuit terminal 3 and ground.
- If 15 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 15 Ω
Connect a test lamp between the control circuit terminal 4 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 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 E42 Tail Lamp Assembly.