Circuit Description
The brake pedal position sensor (BPPS) is used by the body control module (BCM) to determine the brake pedal angle for various electrical components. The BPPS is a potentiometer type sensor with 3 circuits: a 10-volt reference circuit, a low reference circuit, a brake apply sensor signal circuit. The BCM provides the BPPS with 10 volts on the 10-volt reference circuit and a ground on the low reference circuit. Application of the BPPS rotate from the closed brake pedal position to the full apply position provides the BCM with a signal voltage from less than 1 volt to greater than 9 volts through the BPPS signal circuit. When the conditions for running this DTC are met, the BCM will use the brake fluid pressure sensor to determine if the predicted operating range of the BPPS is correct. If the BCM detects the BPPS voltage is out of the predicted range, the BCM will send a class 2 message to the electronic brake control module (EBCM) to set DTC C0161. The EBCM will set DTC C0131 or C0132 for a brake fluid pressure sensor fault. The BCM will set DTC C0277, C0278, or C0870 if a fault is detected in the BPPS .
DTC Descriptors
This diagnostic procedure supports the following DTCs:
| • | DTC C0161 ABS/TCS Brake Switch Circuit Malfunction |
| • | DTC C0277 Brake Pedal Position Sensor Circuit |
| • | DTC C0278 Brake Pedal Position Sensor Not Calibrated |
| • | DTC C0870 Device Voltage Reference Output {single or 1} Circuit |
Conditions for Running the DTC
| • | The ignition switch is ON. |
| • | The DTC can be set after system initialization. |
Conditions for Setting the DTC
| • | The BCM detects a failure in the BPPS system. |
| • | The BCM receives a signal from the sensor indicating the brake pedal is applied, the driver commanded throttle, and brake fluid pressure sensor is less then 5 bars (73 psi) for 60 seconds. |
| • | The BCM receives a signal from the sensor indicating the brake is not applied, and the brake fluid pressure sensor is greater then 15 bars (218 psi) for 1 second. |
Action Taken When the DTC Sets
If equipped, the following actions occur:
| • | The EBCM disables the antilock brake system (ABS)/traction control system (TCS)/vehicle stability enhancement system (VSES) for the duration of the ignition cycle. |
| • | A malfunction DTC will set. |
| • | The ABS indicator turns ON. |
Conditions for Clearing the DTC
| • | The condition for the DTC is no longer present and the DTC is cleared with a scan tool. |
| • | The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles. |
Diagnostic Aids
It is possible to set DTC C0161 if the vehicle is driven with the brake and the accelerator pedal applied at the same time for more than 60 seconds.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step checks if there is other DTCs that can cause the BPPS failure.
-
This step checks to see if the DTC will reset as current.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Antilock Brake System Schematics Connector End View Reference: Antilock Brake System Connector End Views and Computer/Integrating Systems Connector End Views | |||
1 |
Does the scan tool display DTC C0277, C0278, or C0870? | Go to Step 2 | |
2 | Select the display DTCs function on the scan tool for the EBCM. Does the scan tool display DTC U1000 or U1064? | Go to Step 3 | |
Verify the state of the brake lamps with the brake pedal RELEASED. Are all of the stop lamps ON? | Go to Stop Lamps Always On | Go to Step 4 | |
4 | Select the display DTCs function on the scan tool for the EBCM. Does the scan tool display DTC C0131 or C0132? | Go to Step 5 | |
5 |
Does the scan tool value read greater then 15 bars (218 psi)? | Go to Brake Pressure Modulator Valve Pressure Sensor Replacement | Go to Step 6 |
6 | Confirm that the brake pedal position sensor (BPPS) is adjusted to the correct position. Is the BPPS adjustment correctly? | Go to Step 7 | Go to Learn Home Procedure in the BCM special function |
Did DTC C0161 reset? | Go to Step 8 | Go to Diagnostic Aids | |
8 | Replace the BPPS. Refer to Brake Pedal Position Sensor Replacement . Did you complete the replacement? | Go to Step 9 | -- |
9 |
Does the DTC reset? | Go to Step 2 | System OK |
