Diagnostic Instructions

DTC Descriptors

DTC C0035 00: Left Front Wheel Speed Sensor Circuit

DTC C0035 5A: Left Front Wheel Speed Sensor Circuit Erratic Signal

DTC C0040 00: Right Front Wheel Speed Sensor Circuit

DTC C0040 5A: Right Front Wheel Speed Sensor Circuit Erratic Signal

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Left Front Sensor Signal Circuit	C0035 00	C0035 00	--	C0035 5A
Left Front Sensor Low Reference Circuit	C0035 00	C0035 00	C0035 00	C0035 5A
Right Front Sensor Signal Circuit	C0040 00	C0040 00	--	C0040 5A
Right Front Sensor Low Reference Circuit	C0040 00	C0040 00	C0040 00	C0040 5A

Circuit/System Description

As the wheel spins, the wheel speed sensor produces an alternating current (AC) signal. The electronic brake control module (EBCM) uses the frequency of the AC signal to calculate the wheel speed.

Conditions for Running the DTC

C0035 00 or C0040 00

C0035 5A or C00405 A

Conditions for Setting the DTC

Action Taken When the DTC Sets

Conditions for Clearing the DTC

Diagnostic Aids

If 2 or more wheel speed sensors are inoperative diagnose each wheel speed sensor individually.

C0035 5A, 00 or C0040 5A, 00

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

Connector End View Reference

Component Connector End Views

Description and Operation

ABS Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for Scan Tool Information

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 EBCM.
2. Ignition ON, test for 0 volts between the low reference circuit terminals of the appropriate sensor listed below and ground.

•	LF Sensor circuit terminal 13

•	RF Sensor circuit terminal 27

⇒	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.

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

•	LF Sensor circuit terminal 12

•	RF Sensor circuit terminal 26

⇒	If not 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.

•	LF Sensor circuit terminal 13

•	RF Sensor circuit terminal 27

⇒	If not 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.

•	LF Sensor circuit terminal 12

•	RF Sensor circuit terminal 26

⇒	If not 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 wheel speed sensor.
7. Test for less than 2 ohms between the appropriate signal circuit terminals listed below.

•	LF Sensor circuit terminals 12 at the EBCM harness connector, and terminal A at the WSS harness connector

•	RF Sensor circuit terminals 26 at the EBCM harness connector, and terminal A 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.

8. Test for less than 2 ohms between the appropriate low reference circuit terminals listed below.

•	LF Sensor circuit terminals 13 at the EBCM harness connector, and terminal B at the WSS harness connector

•	RF Sensor circuit terminals 27 at the EBCM harness connector, and terminal B 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.

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. Test for 850-1350 ohms of resistance between terminal A and terminal B of the wheel speed sensor.

⇒	If not within the specified range, replace the wheel speed sensor.

3. Test for greater than 100 mV AC voltage between terminal A and terminal B of the wheel speed sensor, when spinning the wheel.

⇒	If not within the specified range, replace the wheel speed sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for EBCM replacement, setup, and programming