GM Service Manual Online
For 1990-2009 cars only

DTC C0131 Greater than or equal to 8600lb GVW

Diagnostic Instructions

    • 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.

DTC Descriptors

DTC C0131 01: ABS Pressure Circuit Short to Battery

DTC C0131 03: ABS Pressure Circuit Voltage Below Threshold

DTC C0131 06: ABS Pressure Circuit Short to Ground or Open

DTC C0131 0F: ABS Pressure Circuit Erratic

DTC C0131 4B: ABS Pressure Circuit Calibration not Learned

DTC C0131 5A: ABS Pressure Circuit Plausibility Failure

DTC C0131 55: ABS Pressure Circuit Expected Number of Transitions or Events not Reached

Circuit/System Description

The electronic brake control module (EBCM) monitors the brake pressure sensor. The information the EBCM recieves from the brake pressure sensor is sent through serial data circuits to the trailer brake control module(TBCM). The TBCM uses this information to perform trailer brake functions. The brake pressure sensor is mounted to the master cylinder.

Conditions for Running the DTC

    • The ignition switch is in the ON position.
    • Ignition voltage is greater than 9.5 volts.

Conditions for Setting the DTC

    • Pressure signal does not correlate to estimated Pressure over time.
    • Signal is erratic and changes faster than physically allowed.

Action Taken When the DTC Sets

    • The EBCM disables the vehicle stability enhancement system (VSES) for the duration of the ignition cycle.
    • A DIC message and/or a warning indicator may be illuminated.

Conditions for Clearing the DTC

    • The condition for the DTC is no longer present.
    • The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Reference Information

Schematic Reference

Antilock Brake System Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

ABS Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the brake pressure sensor.
  2. Ignition OFF, test for less than 5 ohm between the low reference circuit terminal A and ground.
  3. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the EBCM.
  4. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal B and ground.
  5. 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 EBCM.
    If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the EBCM.
  6. Verify the scan tool Brake Pressure Sensor Input parameter is less than 8 kPa (1.2 psi).
  7. If greater than the specified range, test the signal circuit terminal C for a short to voltage. If the circuit tests normal, replace the EBCM.
  8. Install a 3A fused jumper wire between the signal circuit terminal C and the 5-volt reference circuit terminal B. Verify the scan tool Brake Pressure Sensor Input parameter is greater than 550 kPa (80 psi).
  9. If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the EBCM.
  10. If all circuits test normal, test or replace the brake pressure sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Brake Master Cylinder Pressure Sensor Replacement
    •  Control Module References for EBCM replacement, setup, and programming

DTC C0131 Less than 8600lb GVW

Diagnostic Instructions

    • 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.

DTC Descriptors

DTC C0131 00: ABS Pressure Circuit

DTC C0131 3A: ABS Pressure Circuit Incorrect Component Installed

DTC C0131 5A: ABS Pressure Circuit Plausibility Failure

Circuit/System Description

The electronic brake control module (EBCM) uses input from the brake pressure sensor for vehicle stability enhancement system (VSES) functions. The brake pressure sensor is internal to the brake pressure modulator valve (BPMV).

Conditions for Running the DTC

    • Ignition ON.
    • Ignition voltage is greater than 10 volts.

Conditions for Setting the DTC

C0131 00

    • Sensor supply voltage is less than 4.5 volts or greater than 5.3 volts for more than 1 sec.
    • Sensor signal voltage is less than 0.12 volts or greater than 3.2 volts for more than 1 sec.

C0131 3A

EBCM has been replaced and the calibration to the brake pressure sensor is outside of programed range.

C0131 5A

    • The EBCM detects the brake pressure does not increase when braking, when it received a message that the brake pedal is applied.
    • The EBCM detects the brake pressure is increasing when braking, and did not receive a message that the brake pedal is applied.
    • Internal pressure sensor fault.

Action Taken When the DTC Sets

    • The EBCM disables the ABS/traction control system (TCS)/vehicle stability enhancement system (VSES) for the duration of the ignition cycle.
    • A DIC message and/or a warning indicator may be displayed.

Conditions for Clearing the DTC

    • The condition for the DTC is no longer present.
    • The EBCM clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids

A C0131 can get set if the ECU is loosely attached to the hydraulic unit. The mountings should be checked for the proper torque.

Reference Information

Schematic Reference

Antilock Brake System Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

ABS Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

C0131 00 or C0131 5A

  1. Apply and release brake pedal. Verify brake lamps operate properly.
  2. If brake lamps do not operate properly, refer to Symptoms - Lighting.
  3. Replace EBCM/BPMV assembly.

C0131 3A

Verify DTC C0131 3A is not set.

If DTC is set, perform the special function, Brake Pressure Sensor Calibration.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Brake Pressure Modulator Valve Replacement
    •  Control Module References for EBCM replacement, setup, and programming