Circuit Description
The wheel speed sensor receives a 12-volt reference voltage from the electronic brake control module (EBCM) and a ground through the chassis of the vehicle. As the wheel spins, the wheel speed sensor sends the EBCM a DC square wave signal. The EBCM uses the frequency of the square wave signal to calculate the wheel speed.
DTC Descriptors
This diagnostic procedure supports the following DTCs:
| • | DTC C0035 LF Wheel Speed Sensor Circuit |
| • | DTC C0040 RF Wheel Speed Sensor Circuit |
| • | DTC C0045 LR Wheel Speed Sensor Circuit |
| • | DTC C0050 RR Wheel Speed Sensor Circuit |
This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description .
DTC Symptom | DTC Symptom Descriptor |
|---|---|
18 | Signal Amplitude Less Than Minimum |
0F | Signal Erratic |
00 | No Additional Information |
Conditions for Running the DTC
C0035 - C0050 18
| • | The ignition is ON. |
| • | Ignition voltage is greater than 8 volts. |
| • | The brake pedal is not pressed. |
| • | No other wheel speed circuit DTCs are set. |
| • | At least two other wheel speeds are not 0 km/h. |
C0035 - C0050 0F
| • | The ignition is ON. |
| • | Ignition voltage is greater than 8 volts. |
| • | The brake pedal is not pressed. |
| • | A DTC is not set for the other wheel speed circuit on the same axle. |
C0035 - C0050 00
| • | The ignition is ON. |
| • | Ignition voltage is greater than 8 volts. |
Conditions for Setting the DTC
C0035 - C0050 18
The code is set when the following conditions exist:
| • | One wheel speed is 0 km/h. |
| • | The remaining wheel speeds are greater than 8 km/h (5 mph). |
| • | The difference between the remaining wheel speeds is less than 11 km/h (7 mph) from each other. |
C0035 - C0050 0F
If the EBCM detects a change in wheel speed that exceeds 20 km/h (12 mph) between two 10 millisecond wheel speed samples. If the condition occurs 3 times in 200 milliseconds, the code is set.
C0035 - C0050 00
The code is set when either of the following conditions exist:
| • | An open or a short to ground is detected on the wheel speed sensor signal circuit by the EBCM. |
| • | A short to voltage is detected on the wheel speed sensor signal circuit by the EBCM. |
Action Taken When the DTC Sets
If equipped, the following actions occur:
| • | The EBCM disables the ABS/TCS for the duration of the ignition cycle. |
| • | The ABS indicator turns ON. |
| • | The Traction OFF indicator turns ON. |
| • | If the other wheel speed sensor on the same axle sets an additional DTC, the EBCM disables the DRP for the duration of the ignition cycle. |
| • | When the EBCM disables DRP, the red Brake warning indicator turns ON. |
Diagnostic Aids
C0035 - C0050 18
Under the following conditions, 2 Wheel Speed Sensor Input is 0 and DTCs are set:
| • | The 2 suspect wheel speeds equal zero for 6 seconds. |
| • | The other wheel speeds are greater than 16 km/h (10 mph). |
| • | The other wheel speeds are within 11 km/h (7 mph) of each other. |
Diagnose each wheel speed sensor individually.
C0035 - C0050 18, 0F, 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:
- 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 40 km/h (25 mph) for at least 30 seconds.
- If the DTC returns, replace the suspected wheel speed sensor or repair the wheel speed sensor wiring.
- Rinse the area thoroughly when completed.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
Measures the voltage of the wheel speed sensor reference voltage circuit in order to determine if the sensor is able to send a signal.
-
The EBCM can not determine a short to ground on a individual wheel speed sensor supply voltage circuits. The EBCM can only detect a short to ground on one side of the vehicle. Therefore if a short to ground is detected on a wheel speed sensor supply voltage circuit, both front and rear wheel speed sensor DTCs are set on the same side of the vehicle.
-
Ensures that the wheel speed sensor is generating a valid DC square wave output.
-
Measures the average amperage output of the wheel speed sensor signal in order to detect an erratic signal.
Step | Action | Value(s) | 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 scan tool indicate that a wheel speed DTC with a symptom byte of 00 is currently set? | -- | Go to Step 4 | Go to Step 3 |
3 | Drive the vehicle at a speed greater than the specified value. Does the scan tool indicate that a wheel speed DTC with a symptom byte of 18 or 0F is currently set? | 24 km/h (15 mph) | Go to Step 8 | Go to Testing for Intermittent Conditions and Poor Connections |
Does the wheel speed reference voltage measure greater than the specified value? | 8 V | Go to Step 6 | Go to Step 5 | |
Test the wheel speed sensor supply voltage circuit for an open or a short to ground. If DTCs are set for front and rear wheels on the same side of the vehicle, test for a short to ground on both sensor supply voltage circuits. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 10 | |
6 | Test the wheel speed sensor signal circuit for an open, short to ground or a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 7 |
7 | Inspect for poor connections at the harness connector of the wheel speed sensor and electronic brake control module (EBCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 11 |
|
Important: If the DMM is not connected properly, a DTC can set. No wheel speed DTCs should be set during this diagnostic.
Does the amperage toggle low to high for the given specified values? | Hi: 11-16 mA Low: 4-8 mA | Go to Step 9 | Go to Step 11 | |
|
Important: If the DMM is not connected properly, a DTC can set. No wheel speed DTCs should be set during this diagnostic. With the DMM still connected, spin the wheel as fast as possible. Does the amperage read steady between the specified value? | 7.5-12 mA | Go to Step 12 | Go to Step 11 | |
10 | Test the wheel speed sensors for an internal open or a short to ground. If DTCs are set for front and rear wheels on the same side of the vehicle, test for a short to ground on both wheel speed sensors . Refer to Circuit Testing and Wiring Repairs . Did you find open or shorted wheel speed sensor? | Go to Step 11 | Go to Step 12 | |
11 |
Does the scan tool indicate that a wheel speed DTC with a symptom byte of 00 is currently set? | -- | Go to Step 12 | Go to Step 13 |
12 | Replace the EBCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the repair? | -- | Go to Step 13 | -- |
13 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
