C0161

DTC C0161

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 Descriptor
DTC C0161 00
- Antilock Brake System (ABS) Brake Switch Circuit

Circuit/System Description

The electronic brake control module (EBCM) monitors the brake pressure sensor voltage, vehicle speed, and a serial data message from the BCM that the brake pedal is either Applied or Released. When the vehicle is stopping the EBCM detects the brake pressure sensor voltage increases and correlates the readings to the serial data message from the BCM that the brake pedal is applied, and the vehicle is slowing down, or when the vehicle is accelerating, the brake pedal is Released and brake pressure sensor voltage returns to 0 volts.

Conditions for Running the DTC

* The vehicle speed is greater than 16 km/h (10 mph).
* The ignition voltage is greater than 9.5 volts.
* No brake pressure DTCs are detected.

Conditions for Setting the DTC

* The EBCM detects the vehicle speed greater than 21 km/h (13 mph), the brake pedal is Applied for 1 minute, and brake pressure sensor input voltage is at 0 V.
* The EBCM detects the vehicle speed decreases, the brake pedal is Released and the brake pressure sensor input voltage increases.

Action Taken When the DTC Sets

* The EBCM disables the antilock brake system (ABS), traction control system (TCS) and 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 40 consecutive drive cycles.

Note: During normal diagnostic and/or repair verification technicians may find that the ABS, Traction Control and/or Stabilitrak indicators may be ON with NO DTCs displayed by the EBCM. Do not replace the EBCM for this condition.

If the ABS, Traction Control and/or Stabilitrak telltales are ON with no DTCs set, perform the following steps:

1. Remove the key from the ignition, open and close the driver's door to turn off retained accessory power (RAP), and wait 60 seconds.
2. Ignition ON, if the ABS, Traction Control and/or Stabilitrak telltales are still illuminated, operate the vehicle at speeds greater than 15 km/h (10 mph) to complete the self test. The EBCM should request all telltale indicators to turn OFF.
3. If the telltales remain ON with no DTCs set after the drive cycle, disconnect the battery for at least 60 seconds then reconnect the battery.
4. Operate the vehicle at speeds greater than 40 km/h (25 mph), the EBCM should request all telltale indicators to turn OFF.

Diagnostic Aids

DTC C0161 00 can set if the vehicle accelerates with the brake applied.

Reference Information
Schematic Reference

Antilock Brake System Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
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 (Programming and Relearning)for scan tool information

Circuit/System Verification

1. Verify that DTC C0277 or C0890 is not set.

• If DTC is set, refer to DTC C0277 or C0890 (C0277).

2. Ignition ON, observe the scan tool EBCM BPP Signal parameter. The reading should be Released and change between Applied and Released when pressing and releasing the brake pedal.

• If not within the specified value, perform the scan tool BCM BPP Sensor Calibration procedure. Refer to Brake Pedal Position Sensor Calibration (). If the DTC resets, replace the brake pedal position sensor.

3. Ignition ON, observe the scan tool EBCM Brake Pressure Sensor Input Voltage parameter. The reading should be 0 V and change between 0-2 V when pressing and releasing the brake pedal.

• If not within the specified value, perform the scan tool EBCM special functions Brake Pressure Sensor Calibration. If the DTC resets, replace the brake pressure modulator valve assembly.

Repair Instructions

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

* Brake Pedal Position Sensor Replacement ()
* Brake Pressure Modulator Valve Replacement (Brake Pressure Modulator Valve Replacement)
* Control Module References (Programming and Relearning)for EBCM replacement, programming and setup