Antilock Brake System
DTC C0045 or C0050 (With JL4)
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 C0045 00
- Left Rear Wheel Speed Sensor Circuit
DTC C0045 5A
- Left Rear Wheel Speed Sensor Circuit Erratic Signal
DTC C0050 00
- Right Rear Wheel Speed Sensor Circuit
DTC C0050 5A
- Right Rear Wheel Speed Sensor Circuit Erratic Signal
Diagnostic Fault Information
Circuit/System Description
The wheel speed sensor receives ignition voltage from the electronic brake control module (EBCM) and provides a DC square wave signal back to the module. As the wheel spins, the EBCM uses the frequency of the square wave signal to calculate the wheel speed.
Conditions for Running the DTC
C0045 00 or C0050 00
* The ignition is ON.
* Ignition voltage is greater than 9.5 volts.
C0045 5A or C0050 5A
* The ignition is ON.
* Ignition voltage is greater than 9 volts.
* The brake pedal is not pressed.
* A DTC is not set for the other wheel speed circuit on the same axle.
Conditions for Setting the DTC
* An erratic signal output of the wheel speed sensor is detected.
* A short to voltage, open or ground is detected on the wheel speed sensor signal circuit.
* A open or short to ground in the wheel speed sensor circuit supply voltage.
* A missing wheel speed sensor signal
Action Taken When the DTC Sets
* The amber ABS indicator turns ON.
* The Traction Control indicator turns ON.
* The driver information center (DIC) displays the warning message.
Conditions for Clearing the DTC
* The condition for setting the DTC is no longer present.
* The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.
Diagnostic Aids
* Inspect the back of the wheel bearing on the encoder surface for metal debris that could cause an erratic reading with the sensor. Do not use a magnet to clean the debris, or damage to the encoder ring may occur.
* If 2 or more wheel speed sensors are inoperative diagnose each wheel speed sensor individually.
* An ECE 13 response may be required, after repairs are made, and DTCs are cleared, operate the vehicle at speeds greater than 15 km/h (10 mph) to complete the self test, and the EBCM will turn off the ABS indicator.
If the customer comments that the ABS indicator is ON only during moist environmental conditions: rain, snow, vehicle wash, etc., inspect the wheel speed sensor wiring for signs of water intrusion. If the DTC is not current, clear all DTCs and simulate the effects of water intrusion by using the following procedure:
1. Spray the suspected area with a 5 percent saltwater solution. To create a 5 percent saltwater solution, add 2 teaspoons of salt to 8 fl oz of water (10 g of salt to 200 ml of water).
2. Test drive the vehicle over various road surfaces: bumps, turns, etc., above 40 km/h (25 mph) for at least 30 seconds.
3. Rinse the area thoroughly when completed.
Reference Information
Schematic Reference
Antilock Brake System Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views
Description and Operation
ABS Description and Operation (With JL4) (ABS Description and Operation (With RPO JL4))ABS Description and Operation (Without JL4) (ABS Description and Operation (Without RPO JL4))
Electrical Information Reference
* Circuit Testing
* Connector Repairs
* Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs
Scan Tool Reference
Control Module References for Scan Tool Information
Circuit/System Verification
Observe the scan tool Wheel Speed Sensor parameter. The reading should be the same speed on all sensors when driving in a straight line at a speed greater than 20 km/h (13 mph).
Circuit/System Testing
It is recommended that Component Testing is performed before Circuit Testing when diagnosing wheel speed sensors.
1. Ignition OFF, disconnect the harness connector at the EBCM.
2. Ignition ON, test for less than 1 volt between the low reference circuit terminals of the appropriate sensor listed below and ground .
* LR Sensor circuit terminal 20
* RR Sensor circuit terminal 31
• If greater than the specified value, test the low reference circuit for a short to voltage. If the circuit tests normal, replace the wheel speed sensor.
3. Test for less than 1 volt between the signal circuit terminals of the appropriate sensor listed below and ground.
* LR Sensor circuit terminal 33
* RR Sensor circuit terminal 19
• If greater than the specified value, test the signal circuit for a short to voltage. If the circuit tests normal, replace the wheel speed sensor.
4. Ignition OFF, test for infinite resistance between the low reference terminals of the appropriate sensor listed below and ground.
* LR Sensor circuit terminal 20
* RR Sensor circuit terminal 31
• If less than the specified value, test the low reference circuit for a short to ground. If the circuit tests normal, test or replace the wheel speed sensor.
5. Test for infinite resistance between the following signal circuit terminals of the appropriate sensor listed below and ground.
* LR Sensor circuit terminal 33
* RR Sensor circuit terminal 19
• If less than the specified value, test the signal circuit for a short to ground. If the circuit tests normal, test or replace the wheel speed sensor.
6. Ignition OFF, disconnect the harness connector at the appropriate WSS.
7. Test for less than 2 ohms between the appropriate low reference circuit terminals listed below.
* LR Sensor circuit terminals 20 at the EBCM harness connector, and terminal A at the WSS harness connector
* RR Sensor circuit terminals 31 at the EBCM harness connector, and terminal A at the WSS harness connector
• If greater than the specified value, test the low reference circuit for an open or high resistance. If the circuit tests normal, test or replace the wheel speed sensor.
8. Test for less than 2 ohms between the appropriate signal circuit terminals listed below.
* LR Sensor circuit terminals 33 at the EBCM harness connector, and terminal B at the WSS harness connector
* RR Sensor circuit terminals 19 at the EBCM harness connector, and terminal B at the WSS harness connector
• If greater than the specified value, test the signal circuit for an open or high resistance. If the circuit tests normal, test or replace the wheel speed sensor.
9. If all circuits test normal, replace the EBCM.
Component Testing
1. Ignition OFF, disconnect the harness connector at the suspect wheel speed sensor.
2. Ignition On, test at the harness connector for 10-12 volts between the signal circuit terminal, and low reference circuit terminal.
• If not within the specified range, perform the Circuit/System Testing procedure.
3. Connect a jumper wire between the signal circuit terminal on the harness side, and to the wheel speed sensor signal circuit terminal on the WSS.
4. Connect a DMM between the low reference terminal at the WSS, and to the low reference terminal on the harness connector. Set up the DMM to measure mA using the DC scale.
5. Spin the wheel very slowly. Using the DMM MIN/MAX feature, test for 4-8 mA on the MIN capture, and 12-16 mA on the MAX capture. The sensor mA readings should toggle from high to low with in the specified range.
• If not within the specified range, replace the wheel speed sensor.
6. If all sensor circuits test normal, perform the Circuit/System Testing procedure.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
* Rear Wheel Speed Sensor Replacement (Rear Wheel Speed Sensor Replacement)
* Control Module References for EBCM replacement, setup, and programming