Circuit Description
The electronic brake control module (EBCM) provides a common supply voltage to each digital front wheel speed sensor. As the front wheels spin, each wheel speed sensor produces a digital square wave signal. The EBCM uses the frequency of the wheel speed sensor signal to determine wheel speed.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C0035 LF Wheel Speed Sensor Circuit
Conditions for Running the DTC
Both of the conditions listed below may be required to set the DTC.
| • | The ignition is ON. |
| • | The vehicle achieves a speed greater than 40 km/h (25 mph). |
Conditions for Setting the DTC
Any of the following conditions may cause this DTC to set.
| • | The EBCM detects an open or shorted wheel speed sensor for 200 milliseconds. |
| • | The EBCM detects a missing wheel speed sensor signal for one second. If more than one absent wheel speed sensor signal is detected, the condition must be present for 20 seconds to set DTCs. |
| • | The EBCM detects an erratic wheel speed sensor signal for 40 continuous or cumulative milliseconds. |
| • | The supply voltage to the front wheel speed sensors is detected as being at least 5 volts less than the monitored ignition voltage. |
Action Taken When the DTC Sets
If equipped, the following actions occur.
| • | The EBCM disables the Antilock Brake System (ABS). |
| • | The EBCM disables the TCS. |
| • | The EBCM disables dynamic rear proportion (DRP), if all wheel speed inputs have failed. |
| • | The ABS indicator turns ON. |
| • | The ABS fault message is displayed. |
| • | The traction fault message is displayed. |
| • | The brake warning indicator turns ON, if DRP is disabled. |
| • | The brakes message is displayed. |
| • | An ECE 13 response occurs. Refer to ABS Description and Operation for a complete description of ECE 13. |
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 Testing for Intermittent Conditions and Poor Connections , Connector Repairs , Testing for Electrical Intermittents and Wiring Repairs .
If the customers 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.
- Drive the vehicle at a speed greater than 19 km/h (12 mph) for at least 30 seconds.
Repair or replace the suspect harness, if the DTC sets.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
If the DTC sets when the vehicle is not moving, the EBCM is detecting an open or shorted wheel speed sensor or wheel speed sensor circuit.
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A short to ground in the right front wheel speed sensor supply voltage circuit appears electrically the same to the EBCM as a short to ground in the left front wheel speed sensor supply voltage circuit. Therefore, a short to ground in either circuit sets DTC C0035 and each circuit must be tested.
-
The front wheel speed sensors produce a high resolution signal. Therefore, the slightest rotation of the wheel causes the signal to toggle from high to low.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Antilock Brake System Schematics Connector End View Reference: Antilock Brake System Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 |
Does the DTC set? | -- | Go to Step 3 | Go to Diagnostic Aids |
Is DTC C0035 set as a current DTC? | -- | Go to Step 4 | Go to Step 12 | |
4 |
Does the resistance measure less than the specified value? | 45 ohms | Go to Step 6 | Go to Step 5 |
Use a DMM to measure the resistance between the right front wheel speed sensor voltage supply circuit and a good ground. Does the resistance measure less than the specified value? | 45 ohms | Go to Step 6 | Go to Step 9 | |
6 |
Does the resistance measure less than the specified value? | 0 L | Go to Step 8 | Go to Step 7 |
7 | Replace the wheel speed sensor corresponding with the supply voltage circuit that showed a resistance level below specification before the sensor was disconnected. Refer to Wheel Hub/Speed Sensor Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- |
8 | Repair the short to ground in the corresponding wheel speed sensor supply voltage circuit. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 17 | -- |
9 |
Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 11 |
10 | Test the left front wheel speed sensor supply voltage circuit for an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 11 |
11 |
Does the amperage measure within the specified range? | 4-16 mA | Go to Step 15 | Go to Step 13 |
Does the amperage toggle from lower measurement to higher measurement within the specified ranges? | Low signal: 4-8 mA High signal: 12-16 mA | Go to Step 15 | Go to Step 13 | |
13 | Inspect for poor connections at the harness connector of the left front wheel speed sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 14 |
14 | Replace the wheel speed sensor. Refer to Wheel Hub/Speed Sensor Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- |
15 | Inspect for poor connections at the harness connector of the EBCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 16 |
16 | Replace the EBCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 17 | -- |
17 |
Does the DTC reset? | -- | Go to Step 3 | System OK |
