C127D
DTC C0161 or C127D
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 C0161 00
- Antilock Brake System (ABS) Brake Switch Circuit
DTC C127D
- Antilock Brake System (ABS) Brake Switch Circuit
DTC C0161 04
- Antilock Brake System (ABS) Brake Switch Circuit Open Circuit
DTC C0161 0E
- Antilock Brake System (ABS) Brake Switch Circuit Resistance Below Threshold
Diagnostic Fault Information
Circuit/System Description
The brake pedal switch sends a signal to the electronic brake control module (EBCM) when the brake pedal is applied.
Conditions for Running the DTC
C0161 00, C0161 04 or C127D
* The ignition is ON.
* The ignition voltage is greater than 10 volts.
* The brake pedal is applied.
C0161 0E
* Ignition ON.
* The vehicle speed is greater than 15 km/h (9 mph).
* The ignition voltage is greater than 10 volts.
* The accelerator pedal position is greater than 20 percent.
Conditions for Setting the DTC
C0161 04
The brake pedal switch is sensed as unapplied while the pressure sensor and travel sensor indicate the brake pedal is applied.
C0161 00, C0161 0E or C127D
The brake pedal is sensed as applied while the vehicle speed is greater than 15 km/h (9 mph).
Action Taken When the DTC Sets
* The ABS/traction control system (TCS)/vehicle stability enhancement system (VSES), remains functional.
* A DIC message and/or a warning indicator may be displayed.
Conditions for Clearing the DTC
* The condition for setting the DTC is no longer present.
* The EBCM clears the history DTC when a current DTC is not detected in 40 consecutive drive cycles.
Reference Information
Schematic Reference
Antilock Brake System Schematics [1][2]Antilock Brakes / Traction Control Systems
Connector End View Reference
Component Connector End Views Connector 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 Verification
Ignition ON, use a scan tool to observe the EBCM Brake Switch Status parameter while applying and releasing the brake pedal. The reading should change between Applied and Released.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the stop lamp switch.
2. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal B and ground.
• If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test the signal circuit terminal A for a short to ground.
3. Verify the EBCM Brake Switch Status parameter displays Released.
• If not the specified value, test the signal circuit terminal A for a short to voltage. If the circuit tests normal, replace the EBCM.
4. Install a 3A fused jumper wire between the signal circuit terminal A and the ignition circuit terminal B. Verify the scan tool EBCM Brake Switch Status is Applied.
• If not the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the EBCM.
5. If all circuits test normal, test or replace the stop lamp switch.
Component Testing
1. Ignition OFF, disconnect the harness connector at the stop lamp switch.
2. Test for infinite resistance between the signal terminal A and the ignition terminal B with the switch in the open position.
• If not the specified value, replace the stop lamp switch.
3. Test for less than 1.0 ohms between the signal terminal A and the ignition terminal B with the switch in the closed position.
• If greater than the specified range, replace the stop lamp switch.
4. Install a 3A fused jumper wire between the signal circuit terminal A and the ignition circuit terminal B. Verify the scan tool EBCM Brake Switch Status is Applied.
• If greater than the specified range, replace the stop lamp switch.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Stop Lamp Switch Replacement (With Adjustable Pedals) Stop Lamp Switch Replacement (With Adjustable Pedals)Stop Lamp Switch Replacement (Without Adjustable Pedals) Stop Lamp Switch Replacement (Without Adjustable Pedals)
* Control Module References Control Module References for EBCM replacement, setup, and programming