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: Brake Fluid Pressure Sensor Circuit Malfunction

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Brake Fluid Pressure Sensor Signal Circuit | C0131 00 | C0131 00 | C0131 00 | --

### Circuit/System Description

The electronic brake control module (EBCM) uses input from the brake pressure sensor for more accurate control during an electronic brake assist (EBA) or electronic stability program (ESP) event.

### Conditions for Running the DTC

• | The ignition is ON.

• | Ignition voltage is greater than 8 volts.

### Conditions for Setting the DTC

• | Pressure signal does not correlate to estimated pressure over time.

• | Brake Signal does not correlate to pressure signal.

• | Signal is erratic and changes faster than physically allowed.

### Action Taken When the DTC Sets

• | The EBCM disables the Electronic Stability Control (ESP) for the duration of the ignition cycle.

• | The multi function display (MFD) displays the Stability Ctrl Off message.

### Conditions for Clearing the DTC

• | The condition for setting the DTC is no longer present.

• | The DTC can be cleared using a scan tool.

### Diagnostic Aids

The brake fluid pressure sensor is integral to the brake modulator assembly/EBCM. The brake fluid pressure sensor is not serviceable independently.

### Reference Information

#### Schematic Reference

Antilock Brake System Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References

### Circuit/System Verification

With scan tool installed, clear the DTCs then drive the vehicle in a straight line at a speed greater than 20 km/h (13 mph). If the DTC did not set as a current DTC see diagnostic aids.

### Circuit/System Testing

Important: If DTC B3445 is set to current diagnose it first. Refer to DTC B3445 .

1. Apply and release brake pedal. Verify brake lamps operate correctly. If brake lamps do not operate correctly, refer to Symptoms - Lighting Systems .
2. Test the stop lamp supply voltage circuit for a short to voltage, short to ground, an open or high resistance.

⇒ | If the stop lamp circuit tests normal, replace the brake modulator assembly/EBCM.

### Repair Instructions

• | Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Brake Pressure Modulator Valve Assembly Replacement

• | Electronic Brake Control Module Replacement

• | Control Module References for EBCM replacement, setup, and programming