For 1990-2009 cars

### 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: 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 Verification

#### C0131 00 or C0131 5A

1. Apply and release brake pedal. Verify brake lamps operate properly.

⇒ | If brake lamps do not operate properly, refer to Symptoms - Lighting.

2. Replace EBCM/BPMV assembly.

#### C0131 3A

Verify DTC C0131 3A is not set.

⇒ | If DTC is set, perform the scan tool EBCM 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