DTC C0045 or C0050. GMC Truck Acadia

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2007 🢒 Acadia - 2WD 🢒 Driver Information and Entertainment 🢒 Cellular, Entertainment, and Navigation 🢒 DTC C0045 or C0050

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 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	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Left Rear Sensor Signal Circuit	C0045 00	C0045 00	C0045 00	C0045 5A
Left Rear Sensor Low Reference Circuit	--	C0045 00	--	C0045 5A
Right Rear Sensor Signal Circuit	C0050 00	C0050 00	C0050 00	C0050 5A
Right Rear Sensor Low Reference Circuit	--	C0050 00	--	C0050 5A

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 illuminates.

•	The Traction Control indicator illuminates.

•	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.

•	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

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.

•

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:

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).
Test drive the vehicle over various road surfaces, bumps, turns, etc., above 50 km/h (31 mph) for at least 20 seconds.
If the DTC returns, replace the suspected wheel speed sensor or repair the wheel speed sensor wiring.
Rinse the area thoroughly when completed.

Reference Information

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

Scan Tool Reference

Scan Tool Data List

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.

Ignition OFF, disconnect the harness connector at the EBCM.
Ignition ON, test for 0 volts 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 not the specified value, test the low reference circuit for a short to voltage. If the circuit tests normal, replace the wheel speed sensor.

Test for 0 volts between the signal circuit terminals of the appropriate sensor listed below and ground.

•	LR Sensor circuit terminal 33

•	RR Sensor circuit terminal 19

⇒	If not the specified value, test the signal circuit for a short to voltage. If the circuit tests normal, replace the wheel speed sensor.

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 not the specified value, test the low reference circuit for a short to ground. If the circuit tests normal, replace the wheel speed sensor.

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 not the specified value, test the signal circuit for a short to ground. If the circuit tests normal, replace the wheel speed sensor.

Ignition OFF, disconnect the harness connector at the wheel speed sensor.
Test for less than 1 ohm of resistance between the low reference terminals of the appropriate sensor listed below.

•	LR Sensor circuit terminals 20 and 2

•	RR Sensor circuit terminals 31 and 2

⇒	If not within the specified range, test the low reference circuit for an open/high resistance.

Test for less than 1 ohm of resistance between the following signal circuit terminals of the appropriate sensor listed below.

•	LR Sensor circuit terminals 33 and 1

•	RR Sensor circuit terminals 19 and 1

⇒	If not within the specified range, test the signal circuit for an open/high resistance.

Test for infinite resistance between the low reference circuit and the signal circuit of the appropriate sensor listed below and ground.

•	LR Sensor circuit terminal 20 and 33

•	RR Sensor circuit terminal 31 and 19

⇒	If not the specified value, test the appropriate circuit for a short together.

If all circuits test normal, replace the EBCM.

Component Testing

Ignition OFF, disconnect the harness connector at the wheel speed sensor .
Connect a 12 volt test lamp between B+ and the wheel speed sensor signal circuit terminal 1.
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.

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.

•	Rear Wheel Speed Sensor Replacement

•	Control Module References for EBCM replacement, setup, and programming