Wheel Speed Sensor: Service and Repair

REMOVAL
1. Splash Shield Removal (Front only).
2. Follow removal steps outlined in the image, noting the following.





3. Use special tool MB991248 or equivalent to remove rear ABS rotor.

NOTE: The front ABS rotor, integrated with the drive shaft, cannot be disassembled.

INSPECTION

Wheel Speed Sensor Check





1. Check whether any metallic foreign material has adhered to the parts shown at the wheel speed sensor tip, and it so, remove it.

NOTE: The section shown can become magnetized because of the magnet built into the wheel speed sensor, with the result that foreign metallic material is attached to it.





2. Measure the resistance between the wheel speed sensor terminals.
Standard value: 1.0 - 1.5 kilo ohms.
If the internal resistance of the wheel speed sensor is not within the standard value, replace with a new wheel speed sensor.

3. Check the wheel speed sensor cable for breakage, damage or disconnection; replace with a new one if problem is found.

NOTE: When checking for cable damage, remove the cable clamp part from the body and then bend and pull the cable near the clamp to check whether or not an intermittent contact results. Check the connector connection and the terminal insertion.

Wheel Speed Sensor Insulation Check





1. Remove all connections from the wheel speed sensor, and then measure the resistance between terminals (1) and (2) and the body of the wheel speed sensor.
Standard value: 100 kilo ohms or more.
2. If the wheel speed sensor insulation resistance is outside the standard value range, replace with a new wheel speed sensor.

ABS Rotor Check





Check whether ABS rotor is broken or deformed, and, if so, replace the ABS rotor.

INSTALLATION
1. Follow removal steps in reverse order for installation, noting the following.





2. Use a press and a socket to install rear ABS Rotor.





3. The clearance between the wheel speed sensor and the ABS rotor's toothed surface is not adjustable, but measure the distance between the sensor installation surface and the ABS rotor's toothed surface.
Standard value: 28.2 - 28.5 mm (1.11 - 1.12 inch).
4. Check wheel speed sensor output voltage.
5. Install Splash Shield (Front only).