Wheel Speed Sensor on Front Axle
Note: Removing and installing ABS system components is identical for FS III and FN 3 brake calipers.
1 ABS wheel speed sensor
^ Before inserting sensor, clean mounting hole inner surface and coat with lubricant, G 000 650
2 Wheel bearing housing
3 Hex socket head bolt, 8 Nm (70 inch lbs.)
4 Splash shield
5 Hex bolt, 7 Nm (62 inch lbs.)
6 Wheel bearing
^ Replace each time after removing
7 Screw
8 Brake disc
9 Wheel hub with ABS wheel speed sensor rotor
^ Pressing out and in
10 Circlip
Wheel speed sensor for front axle, removing and installing
Removing
^ Raise vehicle.
^ Disconnect wheel speed sensor wiring connector -1-.
^ Remove bolt -2- from wheel bearing housing.
^ Remove wheel speed sensor from wheel bearing housing.
Installing
^ Before inserting speed sensor, clean mounting hole inner surface and coat sensor with lubricant G 000 650.
^ Insert speed sensor into mounting hole in wheel bearing housing and tighten bolt to 8 Nm (70 inch lbs.).
^ Connect wheel speed sensor wiring connector.
^ Turn wheels fully to left and right lock and check clearance of speed sensor wiring.
ABS wheel speed sensor rotor for front axle, checking
^ Raise vehicle.
^ Remove wheel.
^ Rotate brake disc and check whether wheel speed sensor rotor is damaged or dirty.
^ If rotor is damaged, remove wheel hub with rotor and replace.
^ Raise vehicle.
^ Remove wheel.
^ Turn wheel hub and measure distance between rotor and speed sensor, -dimension a, all around.
- Dimension a = 0.3 mm (0.0118 in.)
^ If the rotor is not true, remove wheel hub with rotor and replace.
Front wheel speed sensor wiring, removing and installing
Required special tools and equipment
^ VAS 1978 wiring repair set
Removing
^ Obtain radio code on vehicles with coded radio.
^ Disconnect battery.
^ Remove Mass Air Flow (MAF) sensor connector -1- from air filter duct.
^ Remove bolts -2- at air filter -3- and place filter to left side.
^ On vehicles with Diesel engines, remove relay panel above brake booster.
- Release connector from control module (arrow -1-) and pull off (arrow -2-)
^ Using a screwdriver, lift cover of multi-pin connector and remove.
^ Using a small screwdriver, push purple latch in direction of arrow.
Pin assignment of harness connector T25 and ABS Control Module (W/EDL) -J104
Pin Connected to component:
19 + 20 Right Front ABS Wheel Speed Sensor -G45
1 + 2 Left Front ABS Wheel Speed Sensor -G47
^ Using extractor tool from wiring harness repair set VAS 1978, push out applicable terminals.
^ Disconnect wheel speed sensor wiring connector.
^ Replace faulty wheel speed sensor wiring.
^ Connect speed sensor to speed sensor wiring.
^ Secure speed sensor wiring (arrows).
Note: Make sure the wiring is not twisted in the wheel well.
^ Install pin connectors in connector housing.
^ Using installation tool from VAS 1978, push individual wire seals to stop.
^ Secure terminals by engaging purple latch and install cover of multi-pin connector.