Antilock Brake System
DTC C0045 or C0050
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach. Initial Inspection and Diagnostic Overview
* 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 9.5 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.
* Wheel speed sensor power supply is less than 7.6 volts.
* A missing wheel speed sensor signal
Action Taken When the DTC Sets
* The EBCM disables the Antilock Brake System (ABS)/Traction Control System (TCS)/Vehicle Stability Enhancement System (VSES) for the duration of the ignition cycle.
* The electronic brake distribution (EBD) does not function optimally.
* The ABS indicator turns ON.
* The Traction Control indicator turns ON.
* The driver information center (DIC) displays the Service Stability System 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
If 2 or more wheel speed sensors are inoperative diagnose each wheel speed sensor individually.
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 50 km/h (31 mph) for at least 20 seconds.
3. If the DTC returns, replace the suspected wheel speed sensor or repair the wheel speed sensor wiring.
4. Rinse the area thoroughly when completed.
Circuit/System Verification
Ignition ON, 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
Important: It is recommended that Component Testing is performed before Circuit Testing when diagnosing wheel speed sensors because the module will default and does not supply voltage to the sensor when the DTC is set.
Performing Circuit Testing with EBCM connector disconnected and key on will cause U codes to set. Clear DTCs after performing the test.
1. Ignition OFF, disconnect the harness connector at the suspect wheel speed sensor.
2. Ignition ON, test for 0 volts between the low reference circuit terminal 2 and ground.
^ If not the specified value, test the low reference circuit for a short to voltage. If the circuit tests normal, replace the EBCM.
3. Disconnect the harness connector at the EBCM.
4. Test for infinite resistance between the low reference circuit terminal 2 and ground.
^ If not the specified value, test the low reference circuit for a short to ground.
5. Test for less than 1 ohm of resistance between the low reference circuit terminals of the appropriate sensor listed below.
^ LR sensor terminals 2 and 20
^ RR sensor terminals 2 and 31
^ If greater than the specified range, test the low reference circuit for an open/high resistance.
6. Test for infinite resistance between the signal circuit and ground.
^ If not the specified value, test the signal circuit for a short to ground.
7. Test for less than 1 ohm of resistance between the signal circuit terminals.
^ LR sensor terminals 1 and 33
^ RR sensor terminals 1 and 19
^ If not within the specified range, test the signal circuit for an open/high resistance.
8. If all circuits test normal, replace the EBCM.
Component Testing
1. Ignition OFF, disconnect the harness connector at the wheel speed sensor.
2. Connect a 12 volt test lamp between B+ and the wheel speed sensor signal circuit terminal 1.
3. Test for 4-8 mA on the low reading between the low reference terminal 2 and ground when spinning the wheel very slow.
^ If not within the specified range, replace the wheel speed sensor.
4. Test for 12-16 mA on the high reading between the low reference terminal and ground when spinning the wheel very slow.
^ If not within the specified range, replace the wheel speed sensor.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
* Rear Wheel Speed Sensor Replacement
* Programming and Relearning Programming and Relearning