Circuit/System Testing

Rear Fog Lamp Switch Malfunction

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the S30 Headlamp Switch, ignition ON.
2. Test for B+ between the B+ circuit terminal 1 and ground.
   • If less than B+ 
   1. Ignition OFF, disconnect the X3 harness connector at the K9 Body Control Module.
   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
   3. 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, replace the K9 Body Control Module.
   • If B+ 
3. Verify a test lamp does not illuminate between the B+ circuit terminal 1 and the signal circuit terminal 12.
   • If the test lamp illuminates 
   1. Ignition OFF, disconnect the X1 harness connector at the K9 Body Control Module.
   2. Test for infinite resistance between the signal 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.
   • If the test lamp does not illuminate 
4. Test for B+ between the B+ circuit terminal 1 and the signal circuit terminal 12.
   • If less than B+ 
   1. Ignition OFF, disconnect the X1 harness connector at the K9 Body Control Module, ignition ON.
   2. Test for less than 1 V between the signal circuit terminal 12 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V
   3. Test for less than 2 Ω in the signal 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 B+ 
5. Test or replace the S30 Headlamp Switch.

Rear Fog Lamps Malfunction

1. Ignition OFF, exterior lamps OFF, disconnect the harness connector at the appropriate E29 Fog Lamp - Rear.
2. Test for less than 10 Ω between the ground circuit at the socket terminal and ground.
   • 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.
   • If less than 10 Ω 
3. Connect a test lamp between the control circuit at the socket terminal and ground, ignition ON.
4. Verify the test lamp turns ON and OFF when commanding the Rear Fog Lamp ON and OFF with a scan tool.
   • If the test lamp is always OFF 
   1. Ignition OFF, disconnect the X5 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.
      • 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 X5 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.
   • If the test lamp turns ON and OFF 
5. Test or replace the inoperative E29 Fog Lamp - Rear.

Rear Fog Lamp Indicator Malfunction

1. Ignition ON.
2. Verify the rear fog lamp indicator turns ON and OFF when commanding the Instrument Cluster All Indicators Test ON and OFF with a scan tool.
   • If the rear fog lamp indicator is always OFF or remains ON 

     Replace the P16 Instrument Cluster.

   • If the rear fog lamp indicator turns ON and OFF 
3. Replace the K9 Body Control Module.