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 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
* Visually inspect the vehicle speed sensor for cracks or damage.
* Ensure the vehicle speed sensor is properly installed.
* Inspect the internal tone ring or gear teeth for damage.
Reference Information
Schematic Reference
Antilock Brake System Schematics [1][2]Antilock Brakes / Traction Control Systems
Connector End View Reference
Component Connector End Views 1-2 Shift Solenoid (SS) Valve (M30)
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
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 Control Module References for EBCM or ECM replacement, programming and setup