GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2007 🢒 Sierra Classic - 4WD 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC C0277

Circuit Description

The brake pedal position (BPP) sensor provides an analog pedal position signal. Its output is hardwired to the electro-hydraulic power steering (EHPS) connector. The signal must be digitized and differentiated within the EHPS module to provide the necessary pedal rate signal.

The EHPS supplies a 5-volt reference through the BPP sensor reference voltage circuit to the BPP sensor. When the brake pedal is being applied, the BPP sensor then sends a variable voltage signal through the BPP sensor signal circuit to the EHPS.

The BPP sensor is a resistive sensor with a total resistance between 3,000-5,000 ohms with a maximum current draw of less than 16 ma. The BPP sensor will output an analog signal that is referenced to 5 volts which may increase or decrease monotonically with brake pedal depression. The sensor analog output shall have a specified electrical output over a mechanical range of 32 degrees rotation of the brake pedal pivot. Out-of-range values will be provided outside of the 32 degrees range.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C0277 Brake Pedal Position Sensor Circuit

Conditions for Running the DTC
    • The EHPS module is in RUN mode.
    • The ignition switch is in the ACC or ON position.
    • Battery voltage is between 12-58 volts.

Conditions for Setting the DTC

The BPP sensor circuit is open or short to battery. Raw BPP sensor is greater than 4.2 volts.

Action Taken When the DTC Sets
    • System operation is reduced.
    • The SERVICE BRAKE SYSTEM message will be displayed.
    • Ramp the motor speed input to the commanded flow resolved from a default brake pedal position.
    • Stores DTC C0277 in the powertrain control module (PCM).
    • History DTC C0277 will be set in the PCM.

Conditions for Clearing the DTC
    • The BPP sensor supply voltage is back within range.
    • Using the scan tool
    • A history DTC will clear after 255 consecutive ignition cycles if the condition for the malfunction is no longer present.

Diagnostic Aids

It may be necessary to check Testing for Intermittent Conditions and Poor Connections .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step checks the BPP sensor data parameters.

    2.

  2. This step tests for an open or short to battery in the BPP sensor signal circuit.

    3.

  3. This step tests for an open or short to voltage in the BPP sensor 5-volt reference circuit.

    4.

  4. This step tests for an open or short to battery voltage in the BPP sensor low reference circuit.

    5.

  5. This step checks for poor connections at the BPP sensor harness connector.

    6.

  6. This step tests to see if DTC C0277 resets.

    7.

  7. This step checks for poor connections at the BPP sensor control module connector.

Step

Action

Yes

No

Schematic Reference: Power Steering Schematics

Connector End Views Reference: Power Steering Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Turn ON the ignition, with the engine OFF.
  2. With a scan tool, observe the brake pedal position (BPP) sensor Input and Output Voltage parameters in the data list for the EHPS control module.
  3. 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

Test for an open or short to battery in the BPP sensor signal circuit. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 11

Go to Step 4

4

Test for an open or short to battery positive voltage in the BPP sensor 5-volt reference circuit. Refer to Circuit Testing .

Did you find and correct the condition?

Go to Step 11

Go to Step 5

5

Test for an open or short to battery positive voltage in the BPP sensor low reference circuit. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 11

Go to Step 6

6

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

Did you find and correct the condition?

Go to Step 11

Go to Step 7

7

Important: Always perform the calibration procedure for the BPP sensor. Refer to Brake Pedal Position Sensor Calibration .

Replace the BPP sensor.

Did you complete the repair?

Go to Step 8

--

8

  1. Turn ON the ignition, with the engine OFF.
  2. Apply and release the brake pedal.

Does DTC C0277 reset?

Go to Step 9

Go to Step 11

9

Inspect for poor connections at the harness connector of electro-hydraulic power steering (EHPS) control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 11

Go to Step 10

10

Important: Always perform the calibration procedure for the BPP sensor. Refer to Brake Pedal Position Sensor Calibration .

Replace the EHPS powerpack. Refer to Power Steering Pump Replacement .

Did you complete the replacement?

Go to Step 11

--

11
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does DTC C0277 reset?

Go to Step 2

System OK