GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Saab 🢒 2007 🢒 9-7x 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC C0131

Circuit Description

The master cylinder pressure sensor is located within the brake pressure modulator valve (BPMV). The master cylinder pressure sensor signal, to the electronic brake control module (EBCM), increases as hydraulic pressure in the front brake circuit increases.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C0131 Antilock Brake System (ABS)/Traction Control System (TCS) Pressure Circuit

Conditions for Running the DTC
    • The ignition is ON.
    • The vehicle stability enhancement system (VSES) sensors have been successfully initialized or the message center has displayed the stability system disabled message due to an unsuccessful initialization attempt. Refer to ABS Description and Operation for a complete explanation of VSES sensor initialization.
    • The vehicle is being driven relatively straight and level at a speed greater than 36 km/h (23 mph).
    • The transmission is not shifted into neutral or low gear.
    • The parking brake is released.

Conditions for Setting the DTC

Any of the following conditions may cause the DTC to set.

    • The EBCM detects open master cylinder pressure sensor circuitry.
    • The EBCM detects shorted master cylinder pressure sensor circuitry.
    • The master cylinder pressure sensor self-test, which occurs at power-up, fails.
    • The zero-pressure signal voltage is not within an acceptable range.
    • The master cylinder pressure is not within an expected tolerance based on deceleration rate and other data available to the EBCM.

Action Taken When the DTC Sets
    • The EBCM disables the VSES.
    • The TCS operates with engine torque reduction only.
    • The stability indicator turns ON.

Conditions for Clearing the DTC

The conditions for setting the DTC are no longer present and you use the scan tool Clear DTCs function.

Diagnostic Aids

Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to the following:

    •  Testing for Electrical Intermittents
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs
    •  Connector Repairs

Test Description

The number below refers to the step number on the diagnostic table.

  1. This step is required for vehicles equipped with a hydro-boost brake assist system only. If the vehicle being serviced has vacuum assisted brakes, proceed to step 4.

Step

Action

Yes

No

Important: Use the scan tool to read both current and history DTCs before proceeding. If DTC C0292 is set, diagnose that DTC before proceeding with diagnostics for C0131.

If DTC C0161 is set, diagnose that DTC before proceeding with diagnostics for C0131.

Schematic Reference: Antilock Brake System Schematics

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Inspect the vehicle for the following and ensure that there is no base brake failure:

    • Dragging brakes
    • Faulty parking brake switch
    • Brake fluid leakage
    • Air in hydraulic system
    • Seized brake calipers
    • Swollen, kinked or otherwise damaged brake hoses

Did you find and correct the condition?

Go to Step 9

Go to Step 3

3

Drive the vehicle in order to verify that the brakes do not self-apply during turning maneuvers.

Do the brakes self-apply during turning maneuvers?

Go to Symptoms - Hydraulic Brakes

Go to Step 4

4
  1. Use the scan tool to clear the DTCs.
  2. Turn OFF the ignition for 5 seconds.
  3. Turn ON the ignition.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 5

Go to Diagnostic Aids

5
  1. Select the vehicle stability enhancement system (VSES) Data Display function on the scan tool.
  2. Observe the Brake Switch Status parameter while pressing and releasing the brake pedal.

Does the Brake Switch Status change while pressing and releasing the brake?

Go to Step 6

Go to DTC C0161

6
  1. Remove the electronic brake control module (EBCM) from the vehicle. Refer to Diagnostic System Check - Vehicle .
  2. Inspect the master cylinder pressure sensor connector within the EBCM for damage or corrosion.

Is there connector damage or corrosion present?

Go to Step 7

Go to Step 8

7

Important: Following EBCM replacement, perform the set-up procedure for the EBCM. Use the scan tool to perform the Tire Size Calibration procedure.

Replace the EBCM. Refer to Diagnostic System Check - Vehicle .

Did you complete the replacement?

Go to Step 9

--

8

Important: Following EBCM replacement, perform the set-up procedure for the EBCM. Use the scan tool to perform the Tire Size Calibration procedure.

Replace the EBCM and the brake pressure modulator valve (BPMV). Refer to Diagnostic System Check - Vehicle .

Did you complete the replacements?

Go to Step 9

--

9
  1. Use the scan tool Clear All Class 2 DTCs function to clear all of the DTCs from all modules.
  2. Turn OFF the ignition for 5 seconds.
  3. Turn ON the ignition.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK