C0138

DTC C0131-C0139

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors
DTC C0131
- Antilock Brake System (ABS) Pressure Circuit

DTC C0136
- Base Brake System Pressure Circuit/Sensor

DTC C0138
- Base Brake System Pressure Circuit/Sensor Low

DTC C0139
- Base Brake System Pressure Circuit/Sensor High

Circuit/System Description

The electronic brake control module (EBCM) uses inputs from 2 internal brake fluid pressure sensors to enhance ABS braking and vehicle stability if equipped.

Conditions for Running the DTC

C0131
* The braking system is not performing an antilock or traction control event.
* No other brake pressure sensor DTCs are set.

C0136
* Ignition ON.
* The 5-volt reference to the brake pressure sensor is in range.

C0138
* The ignition is ON for 1 second and greater than 8 volts.
* The 5-volt reference to the brake pressure sensor is in range.
* DTC C0136 is not set.

C0139
* Ignition ON.
* The 5-volt reference to the brake pressure sensor is in range.
* DTC C0136 is not set.
* Vehicle speed is above 16 km/h (10 mph).

Conditions for Setting the DTC

C0131

The 2 master cylinder pressure sensors do not correlate.

C0136
* The brake fluid pressure sensor signal is greater than 4.9 volts.
* The brake fluid pressure sensor signal is less than 0.15 volt.

C0138

This DTC is set when the vehicle decelerates and the brake pressure signal does not increase. The criteria to set this DTC is listed below:

* The vehicle decelerates from 25 km/h (16 mph) to 10 km/h (6 mph).
* The vehicle decelerates at a rate of 8 km/h (5 mph) per second.
* No increase in the brake pressure sensor signal is detected.

C0139

This DTC is set when the vehicle accelerates and the brake pressure signal is high. The criteria to set this DTC is listed below:

* The vehicle exceeds 40 km/h (25 mph).
* The vehicle accelerates at a rate of 8 km/h (5 mph) per second.
* The brake pressure sensor signal output is above 1034 kPa (150 psi).

Action Taken When the DTC Sets

If equipped, the following actions occur:

* The EBCM disables the antilock brake system (ABS)/traction control system (TCS)/vehicle stability enhancement system (VSES) for the duration of the ignition cycle.
* The ABS indicator illuminates
* The Red brake indicator illuminates.
* The Stability Control indicator illuminates.
* The driver information center (DIC) displays Service Stability control and Service Traction System message.

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

The brake pressure sensor is internal to the brake pressure modulator valve (BPMV) and cannot be diagnosed.

Reference Information
Schematic Reference

Antilock Brake System Schematics [1][2]Antilock Brakes / Traction Control Systems
Connector End View Reference

Component Connector End Views
Description and Operation

ABS Description and Operation Description and Operation
Electrical Information Reference

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

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Testing

1. Verify DTC C0870 is not set.

• If DTC is set, refer to DTC C0870 Antilock Brake System

2. Verify DTC C0131-C0139 is not set.

• If DTC is set, replace the BPMV and verify DTC does not reset. If DTC resets replace the EBCM.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Brake Pressure Modulator Valve Replacement Service and Repair
* Control Module References Control Module References for EBCM replacement, setup, and programming