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. Refer to the following procedures in Wiring Systems:
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:
- Spray the suspected area with a 5 percent salt water solution.
- 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.
Step | Action | Values | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Antilock Brake System Schematics | ||||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | ||||||||
2 |
Does the DTC set? | 13 km/h (8 mph) | Go to Step 3 | Go to Diagnostic Aids | ||||||||
3 |
Does the resistance measure within the specified range? | 700-10,000 ohms | Go to Step 4 | Go to Step 8 | ||||||||
4 |
Does the AC voltage measure greater than the specified value? | 100 mV | Go to Step 5 | Go to Step 8 | ||||||||
5 | Inspect for poor connections at the harness connector of the wheel speed sensor. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 6 | ||||||||
6 |
Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 7 | ||||||||
7 | Inspect for poor connections at the harness connector for the EBCM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 9 | ||||||||
8 | Replace the wheel speed sensor. Refer to Wheel Speed Sensor Replacement . Did you complete the replacement? | -- | Go to Step 10 | -- | ||||||||
9 |
Important: Following EBCM replacement, use the scan tool to perform the Tire Size Calibration procedure. Replace the EBCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup and programming. Did you complete the replacement? | -- | Go to Step 10 | -- | ||||||||
10 |
Does the DTC reset? | -- | Go to Step 2 | System OK | ||||||||
