Circuit/System Testing

Brake Pedal Position Sensor Malfunction

1. Ignition OFF, disconnect the harness connector at the B22 Brake Pedal Position Sensor, ignition ON.
2. Test for less than 1 V between the appropriate low reference circuit terminal listed below and ground.
   • Terminal 2 - with MM1 (Chevrolet)
   • Terminal A - with MM3 (Chevrolet)
   • Terminal 2 (Buick)
   • If 1 V or greater 
   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 low reference circuit 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 less than 1 V 
3. Test or replace the B22 Brake Pedal Position Sensor.

Stop Lamps Malfunction

1. Ignition OFF, exterior lamps OFF, rear hatch latch latched, remove the appropriate bulb listed below.
   • E5 Stop Lamp (Chevrolet)
   • E42 Tail Lamp Assembly (Buick)
2. Test for less than 10 Ω between the appropriate ground circuit terminal listed below and ground.
   • E5L Stop Lamp - Left socket terminal (Chevrolet)
   • E5R Stop Lamp - Right socket terminal (Chevrolet)
   • E42L Tail Lamp Assembly - Left terminal 3 (Buick)
   • E42R Tail Lamp Assembly - Right terminal 3 (Buick)
   • 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 
3. Connect a test lamp between the appropriate control circuit terminal listed below and ground, ignition ON.
   • E5L Stop Lamp - Left socket terminal (Chevrolet)
   • E5R Stop Lamp - Right socket terminal (Chevrolet)
   • E42L Tail Lamp Assembly - Left terminal 2 (Buick)
   • E42R Tail Lamp Assembly - Right terminal 2 (Buick)
4. Verify the test lamp turns ON and OFF when commanding the appropriate Rear Stop/Park Lamp 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 left stop lamp
      • X5 right stop lamp
   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 left stop lamp
      • X5 right stop lamp
   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 
5. Test or replace the appropriate E5 Stop Lamp.

Center High Mount Stop Lamp Malfunction

1. Ignition OFF, disconnect the X2 harness connector at the K9 Body Control Module, ignition ON.
2. Verify a test lamp illuminates between the B+ circuit terminal 1 and ground.
   • If the test lamp does not illuminate and the circuit fuse is good 
   1. Ignition OFF, disconnect the harness connector 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, disconnect the harness connector 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 
3. Ignition OFF, connect the X2 harness connector at the K9 Body Control Module.
4. Ignition OFF, exterior lamps OFF, rear hatch latch latched, disconnect the harness connector at the E6 Center High Mounted Stop Lamp.
5. Test for less than 5 Ω between the ground circuit terminal 2 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 
6. Connect a test lamp between the control circuit terminal 1 and ground, ignition ON.
7. Verify the test lamp turns ON and OFF when commanding the Center Stop Lamp ON and OFF with a scan tool.
   • If the test lamp is always OFF 
   1. Ignition OFF, disconnect the X4 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 X4 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 
8. Test or replace the E6 Center High Mounted Stop Lamp.