C0040

DTC C0035 or C0040

Circuit Description

As the wheels spin, each wheel speed sensor produces an AC signal. The Electronic Brake Control Module (EBCM) uses the frequency of the AC signals to calculate each wheel speed.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

- DTC C0035 Left Front Wheel Speed Sensor Circuit
- DTC C0040 Right Front Wheel Speed Sensor Circuit

Conditions for Running the DTC

- The ignition is ON.
- The vehicle speed is greater than 13 km/h (8 mph).

Conditions for Setting the DTC

Any of the following occurrences may cause the DTC to set.

- The EBCM detects an open or shorted wheel speed sensor circuit for 500 milliseconds.
- The EBCM detects the absence of a wheel speed sensor signal for 5 seconds. If more than one absent wheel speed sensor signal is detected, the condition must be present for 120 seconds to set DTCs.
- The EBCM detects an erratic wheel speed sensor signal for 200 milliseconds.

Action Taken When the DTC Sets

- The EBCM disables the ABS and may disable the dynamic rear proportion (DRP) if more than one wheel speed sensor DTC is set.
- The ABS indicator turns ON.
- The brake warning indicator may turn ON.

The actions above are maintained during subsequent ignition cycles until the EBCM completes a power up self-test. This test concludes when the vehicle achieves a speed greater than 13 km/h (8 mph) and the wheel speeds are verified by the EBCM.

Conditions for Clearing the DTC

The Conditions for Setting the DTC are no longer present and you use the scan tool Clear DTCs function.

Diagnostic Aids

- Thoroughly inspect connections or circuitry that may cause an intermittent malfunction.
- Inspect the following components listed below that may cause the DTC to set:
- Physical damage to encoder ring teeth.
- Debris on the wheel speed sensor or the encoder ring
- Inspect wheel speed sensor mounting surface
- Loose or improperly mounted sensor
- Air gap between the wheel speed sensor and the encoder ring may be too large
- Loose or worn wheel bearing
- Water intrusion in the wiring harness and/or connector

If the customer's concern is that the ABS indicator is on only during humid conditions such as rain, snow or vehicle wash, thoroughly inspect the wheel speed sensor circuits for signs of water intrusion. Use the following procedure in order to help isolate the problem area:

1. Spray the suspected area with a 5 percent salt water solution.
2. Operate the vehicle at a speed greater than 13 km/h (8 mph) for at least 30 seconds.

Repair or replace the suspect harness if the DTC sets.