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: Antilock Brake System (ABS) Pressure CircuitDTC 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
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Antilock Brake System (ABS) Pressure Circuit | C0131 | C0131 | C0131 | C0131 |
Base Brake System Pressure Circuit/Sensor | C0136 | C0136 | C0136 | C0136 |
Base Brake System Pressure Circuit/Sensor Low | C0138 | C0138 | -- | C0138 |
Base Brake System Pressure Circuit/Sensor High | -- | -- | C0139 | -- |
Circuit/System Description
The electronic brake control module (EBCM) uses an input from 2 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
| • | The ignition is ON for 1 second and greater than 8 volts. |
| • | 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
| • | 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. |
| • | 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 will occur:
| • | The EBCM disables the vehicle stability enhancement system (VSES) for the duration of the ignition cycle. |
| • | The EBCM disables the traction control system (TCS) for the duration of the ignition cycle. |
| • | The driver information center (DIC) displays the Service Stability System and Service Traction System message. |
Conditions for Clearing the DTC
| • | The condition for the DTC is no longer present and the DTC is cleared with a scan tool. |
| • | The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles. |
Diagnostic Aids
| • | The brake pressure sensor is mounted to the brake pressure modulator valve (BPMV) under the EBCM and cannot be diagnosed. If equipped, the brake pressure sensor 5-volt reference circuit and low reference circuit is shared with other components in the vehicle stability system. DTCs can set for other components that share circuits with the brake pressure sensor. |
| • | DTC C0870 is set if the 5-volt reference voltage is out of range. |
Reference Information
Schematic Reference
Antilock Brake System Schematics
Connector End View Reference
Antilock Brake System Connector End Views
Description and Operation
Electrical Information Reference
Circuit/System Testing
Important: If DTC C0870 is set, diagnose it first. Refer to DTC C0870 .
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 after completing the diagnostic procedure.
| • | Control Module References for EBCM replacement, setup, and programming |
