• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
• | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
• | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
Brake Pedal Position Sensor 5-Volt Reference | C0277 06, C0870 03 | C0277 06 | 1 | -- |
Center High Mounted Stop Lamp (CHMSL) Relay B+ | 2 | 2 | -- | -- |
Brake Pedal Position Sensor Signal | C0277 06 | C0277 06 | C0277 07 | C0277 09 |
Center High Mounted Stop Lamp (CHMSL) Relay Control | B3903 02 | B3903 05 | B3903 05 | -- |
Center High Mounted Stop Lamp (CHMSL) Control | 2 | 2 | 2 | -- |
Left Rear Stop/Turn Lamp Control | 1 | 1 | 1 | -- |
Right Rear Stop/Turn Lamp Control | 1 | 1 | 1 | -- |
Brake Pedal Position Sensor Low Reference | -- | C0277 07 | 1 | -- |
Center High Mounted Stop Lamp (CHMSL) Ground | -- | 2 | 1 | -- |
Left Rear Stop/Turn Lamp Ground | -- | 1 | 1 | -- |
Right Rear Stop/Turn Lamp Ground | -- | 1 | 1 | -- |
Center High Mounted Stop Lamp (CHMSL) Relay Ground | -- | 2 | -- | -- |
1. Stop Lamps Malfunction 2. Center High Mounted Stop Lamp (CHMSL) Malfunction |
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 voltage to the center high mounted stop lamp (CHMSL) relay coil. When the CHMSL relay receives voltage from the BCM, the relay coil is energized and the CHMSL relay switch contacts close applying battery voltage to the CHMSL, transmission control module (TCM), and engine control module (ECM).
Exterior Lighting Systems Description and Operation
Control Module References for scan tool information
⇒ | If the parameter does not change as the brake pedal is applied and released, refer to Brake Pedal Position Sensor (BPPS) Malfunction. |
⇒ | If the LR stop lamp does not illuminate when commanded, refer to Stop Lamps Malfunction. |
⇒ | If the RR stop lamp does not illuminate when commanded, refer to Stop Lamps Malfunction. |
• | Stop/turn lamp ground terminal C - coupe |
• | Stop/turn lamp ground terminal G - sedan |
⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
⇒ | 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. |
⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
⇒ | If the test lamp illuminates, test the control circuit for a short to voltage. |
⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the control circuit terminal 87 for a short to ground. If the circuit tests normal, test or replace the CHMSL relay. |
⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
⇒ | If the CHMSL does not illuminate, test the control circuit for an open/high resistance. If the circuit tests normal, replace the CHMSL. |
⇒ | 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. |
⇒ | If the test lamp illuminates, test the low reference circuit for a short to voltage. If the circuit tests normal, replace the BCM. |
⇒ | 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. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for BCM replacement, setup, and programming |