GM Service Manual Online
For 1990-2009 cars only

Circuit Description

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 positive voltage to the stop lamps, transmission control module (TCM), engine control module (ECM), and stop lamp relay coil side. The BCM also supplies the stop lamp relay coil with ground. When the stop lamp relay receives battery voltage and ground from the BCM, the relay coil is energized and the stop lamp relay switch contacts close applying battery voltage through the STOP/B/U/LPS fuse to illuminate the center high mounted stop lamp (CHMSL).

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C0277 Brake Pedal Position Sensor Circuit

DTC Symptom

DTC Symptom Descriptor

06

Short to Ground or Open

07

Voltage Above Threshold

09

Rate of Change Above Threshold

Conditions for Running the DTC

Ignition voltage is within the normal operating voltage range.

Conditions for Setting the DTC

DTC C0277 06

The BCM detects an open or short to ground in the brake pedal position sensor signal circuit for 0.5 seconds or greater.

DTC C0277 07

The BCM detects a short to battery voltage in the brake pedal position sensor signal or low reference circuits for 0.5 seconds or greater.

DTC C0277 09

The BCM detects the brake pedal position sensor signal is changing faster than possible under normal operating conditions.

Action Taken When the DTC Sets

    • The Service Vehicle Soon indicator is commanded ON.
    • When DTC C0277 is set as current, the vehicle will not start.
    • If the DTC sets while the vehicle is running, the BCM will activate the brake lights when the vehicles transmission is not in the PARK position and the vehicle is not accelerating.

Conditions for Clearing the DTC

    • The condition responsible for setting the DTC no longer exists.
    • You issue a scan tool CLEAR DTCs command.
    • A history DTC will clear once 50 malfunction-free ignition cycles have occurred.
    • A DTC will not clear the current status until the next ignition cycle.

Diagnostic Aids

Important: The stop lamps will not illuminate unless the ignition is in the ON position. For more detailed information concerning stop lamp operation, refer to Exterior Lighting Systems Description and Operation .

    • If DTC C0277 09 is set, replace the brake pedal position sensor. If the DTC resets, replace the BCM.
    • Thoroughly inspect the wiring and connectors. An incomplete inspection of the wiring and connectors may result in misdiagnosis causing part replacement with the reappearance of the malfunction. If an intermittent malfunction exists, refer to Testing for Intermittent Conditions and Poor Connections .

Step

Action

Yes

No

Schematic Reference: Exterior Lights Schematics

Connector End View Reference: Master Electrical Component List

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the brake pedal position (BPP) sensor parameter in the body control module (BCM) BPP system data list.
  4. Apply and release the brake pedal.

Does the scan tool display a change in the voltage?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

Is DTC C0277 09 present?

Go to Step 9

Go to Step 4

4

Is DTC C0277 07 present?

Go to Step 5

Go to Step 8

5

  1. Turn OFF the ignition.
  2. Disconnect the BCM harness connector C2.
  3. Connect a test lamp between the brake pedal position sensor signal circuit and ground.

Does the test light illuminate?

Go to Step 6

Go to Step 12

6

Test the brake pedal position sensor signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 14

Go to Step 7

7

Test the brake pedal position sensor low reference circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 14

Go to Step 9

8

Test the brake pedal position sensor signal circuit for an open or short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 14

Go to Step 9

9

Inspect for poor connections at the brake pedal position sensor harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 14

Go to Step 10

10

Important: Recalibrate the brake pedal position sensor after replacing. Refer to Brake Pedal Position Sensor Calibration .

Replace the brake pedal position sensor. Refer to Brake Pedal Position Sensor Replacement .

Did you complete the repair?

Go to Step 11

--

11

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Apply and release the brake pedal.

Does the scan tool display DTC C0277 as current?

Go to Step 12

Go to Step 14

12

Inspect for poor connections at the BCM harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 14

Go to Step 13

13

Replace the BCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 14

--

14

  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC.

Does the DTC reset?

Go to Step 2

System OK