The brake pedal position sensor is used to sense the action of the driver application of the brake pedal. The brake pedal position sensor provides an analog voltage signal that will increase as the brake pedal is applied. The body control module (BCM) provides a low reference signal and a 5-volt reference voltage to the brake pedal position sensor. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM will apply battery voltage to the stop lamp relay control circuit, and the center high mounted stop lamp (CHMSL) control circuit.

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, observe the scan tool Brake Applied Output Signal parameter as you apply and unapply the brake pedal. The parameter should change between OFF and ON as the brake pedal is applied and released.

Stop Lamps Malfunction

1. Ignition OFF, disconnect the X3 harness connector at the I/P fuse block.
2. Connect a test lamp between the control circuit terminal 5 and ground.
3. Ignition ON, command the stop lamps ON and OFF by applying and releasing the brake pedal. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.

⇒	If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

4. Ignition OFF, connect the X3 harness connector at the I/P fuse block.
5. Ignition OFF, disconnect the harness connector at the CHMSL.
6. Ignition OFF, test for less than 5.0 ohms between the ground circuit terminal 2 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

7. Connect a test lamp between the control circuit terminal 1 and ground.
8. Ignition ON, command the stop lamps ON and OFF by applying and releasing the brake pedal. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always ON, test the control circuit for a short to voltage.

⇒	If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance.

9. Ignition OFF, connect the harness connector at the CHMSL.
10. Disconnect the X3 harness connector at the underhood fuse block.
11. Ignition OFF, test for less than 5.0 ohms between the ground circuit terminal 2 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

12. Ignition OFF, connect the harness connector at the underhood fuse block.
13. Disconnect the X2 harness connector at the underhood fuse block.
14. Connect a test lamp between the control circuit terminal 15 and ground.
15. Ignition ON, command the stop lamps ON and OFF by applying and releasing the brake pedal. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.

⇒	If the test lamp is always OFF, test the control circuit X2 terminal 15 for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

16. Ignition OFF, disconnect the harness connector at the inoperative stop lamp.
17. Ignition OFF, exterior lamps OFF, test for less than 5.0 ohms between the appropriate ground circuit terminal and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

18. Connect a test lamp between the control circuit terminal and ground.
19. Ignition ON, command the stop lamps ON and OFF by applying and releasing the brake pedal. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the underhood fuse block.

⇒	If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the underhood fuse block.

20. If all circuits test normal, replace the inoperative stop lamp.

Center High Mounted Stop Lamp (CHMSL) Malfunction

1. Ignition OFF, disconnect the harness connector at the CHMSL.
2. Ignition OFF, exterior lamps OFF, test for less than 5.0 ohms between the ground circuit terminal 2 and ground.

⇒	If the test lamp does not illuminate, test the ground circuit for an open/high resistance.

3. Connect a test lamp between the control circuit terminal 1 and ground.
4. Ignition ON, command the stop lamps ON and OFF by applying and releasing the brake pedal. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.

⇒	If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

5. If all circuits test normal, replace the CHMSL.

Brake Pedal Position Sensor (BPPS) Malfunction

1. Ignition OFF, disconnect the harness connector at the BPPS.
2. Ignition ON, verify that a test lamp does not illuminate between the low reference circuit terminal A and ground.

⇒	If the test lamp illuminates, test the low reference circuit for a short to voltage. If the circuit tests normal, replace the BCM.

3. Ignition ON, test for 4.8 volts and 5.2 volts between the 5-volt reference circuit terminal C and ground.

⇒	If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

⇒	If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the BCM.

4. If all circuits test normal, replace the BPPS.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.