Antilock Brake System - Non-Hybrid Less than 3900 kg (8600 lb) GVW
DTC C0055 or P0609
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 C0055 00
- Rear Wheel Speed Sensor Circuit Malfunction
DTC C0055 5A
- Rear Wheel Speed Sensor Circuit Plausibility Failure
DTC P0609
- Vehicle Speed Output Circuit
Diagnostic Fault Information
Circuit/System Description
The electronic control module (ECM) converts the data from the vehicle speed sensor to a 128K pulses/mile signal. The electronic brake control module (EBCM) uses the vehicle speed signal from the ECM in order to calculate the rear wheel speed.
Conditions for Running the DTC
* Ignition ON.
* Ignition voltage is greater than 10 volts.
Conditions for Setting the DTC
C0055 00 or P0609
The EBCM detects a short to voltage, short to ground or an open/high resistance on the rear wheel speed sensor signal circuit.
C0055 5A
The EBCM detects an erratic rear wheel speed signal.
Action Taken When the DTC Sets
* The EBCM disables the Antilock Brake System (ABS) for the duration of the ignition cycle.
* A driver information center 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 100 consecutive drive cycles.
Diagnostic Aids
* Visually inspect the vehicle speed sensor for cracks or damage.
* Ensure the vehicle speed sensor is properly torqued.
* Inspect the internal tone ring or gear teeth for damage.
Reference Information
Schematic Reference
Antilock Brake System Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
ABS Description and Operation (ABS (Non-Hybrid Less than 3900 kg (8600 lb) GVW))
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
Observe the scan tool Rear Wheel Speed parameter. The rear wheel speed reading should be within 2 mph of the front speed sensors when driving in a straight line at a speed greater than 20 km/h (13 mph).
Circuit/System Testing
1. Verify that no DTCs are set in the ECM or TCM.
• If DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code (DTC) List - Vehicle).
2. Ignition OFF, disconnect the harness connector at the EBCM.
3. Ignition ON, test for greater than 10 V between the signal circuit terminal 31 and ground.
• If less than specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
4. Ignition OFF, disconnect the X 1 harness connector at the ECM.
5. Ignition ON, verify that a test lamp does not illuminate between the signal circuit terminal 50 and ground.
• If the test lamp illuminates, test the signal circuit for a short to voltage.
6. If the circuit tests normal, replace the EBCM.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
Control Module References (Programming and Relearning) for EBCM/BPMV or ECM/PCM replacement, setup, and programming