Wednesday, August 27, 2014

1998 Subaru Legacy Abs Wheel Sensor How to

The wheel sensor system on a 1998 Subaru Legacy is directly controlled and monitored by the anti-lock braking system, or ABS, computer. It order to determine which wheels are locking-up, the ABS computer monitors the speed of each wheel individually and compares that speed to the vehicle speed sensor value and the other front wheel. In the event of a wheel lock-up, the ABS computer selectively limits brake pressure until the wheels return to a normal rolling condition. Replacement wheel speed sensors are available for purchase from auto parts stores, Subaru dealerships, and online parts websites.

Instructions

Front Sensor Removal

    1

    Break the lug nuts loose with a lug nut wrench. Raise the front of the vehicle with a jack and support it with jack stands. Remove the lug nuts and tire.

    2

    Locate the wheel speed sensor on the inside of the steering knuckle. It is made from black plastic and has a single wire protruding from it that runs up the inside of the strut assembly. Disconnect the sensor connector inside the engine compartment.

    3

    Remove the bolts holding the sensor harness to the strut assembly with a ratchet and metric socket. Remove the bolts holding the wheel sensor to the knuckle housing with a ratchet and metric socket.

    4

    Remove the sensor from the housing by gripping the sensor between your thumb and foinger and slowly twisting it back and forth while pulling out of its mounting hole.

Front Sensor Installation

    5

    Slide the new sensor into its mounting hole on the steering knuckle flange. Insert a feeler gauge between the sensor reluctor wheel and the sensor hole. Press the sensor down into its mounting hole and set the clearance using the feeler gauge. The specified value is 0.9 to 1.4 mm.

    6

    Install the sensor retaining bolt and tighten it to 17 to 31 foot-pounds using a torque wrench.

    7

    Feed the sensors wire up to the engine compartment and reconnect it to its primary electrical connector. Position the sensor wire bracket on the strut assembly and reinstall the bracket retaining bolt. Tighten the bolt to 17 to 31 foot-pounds using a torque wrench. Reinstall the tire and lug nuts. Lower the vehicle to the ground and tighten the lug nuts to 65 foot-pounds, plus or minus 7 foot-pounds.

    8

    Check to make sure that the sensor wire isnt distorted or strangled. Test drive the vehicle to make sure that the sensor operates properly and that no ABS error lights illuminate on the dash board.

Rear Sensor Removal

    9

    Break the rear lug nuts loose with a lug nut wrench. Raise the rear of the vehicle with a jack and support it with jack stands. Remove the lug nuts and tires. Remove the bolts holding the front seat cushion hinges to the body with a socket and metric ratchet. Lift up the front edge of the seat cushion and detach the rear hooks from back of the seat. Remove the lower seat cushion from the vehicle.

    10

    Remove the bolts holding the lower-edge of the back cushion to the body. Pull the release strap to release the folding lock on the top of the back cushion. Fold the cushion down toward the body and disengage its retaining hooks. Remove the back cushion from the vehicle. Disconnect the ABS connector thats beneath the rear seat and push the wire through the rubber grommet hole in the body.

    11

    Slide underneath the rear of the vehicle on a mechanics creeper and remove the bolt holding the rear ABS sensor to the backing plate behind the wheel hub. Remove the bolt holding the sensor wire to the trailing link. Pull the sensor out of the backing plate and remove the sensor assembly from the vehicle.

Rear Sensor Installation

    12

    Set the sensor wire into position on the trailing link and reinstall the trailing link bolt. Tighten it to 17 to 31 foot-pounds using a torque wrench. Reinstall the ABS sensor into the backing plate and set the gap between the backing plate and the sensor with a feeler gauge; the specified value is 0.7 to 1.2 mm. Tighten the sensors retaining bolt to 17 to 31 foot-pounds with a torque wrench.

    13

    Feed the ABS wire through the rubber grommet and into the cabin, then reconnect the ABS sensors electrical connector inside the vehicle. Set the seat back cushion into position and attach the lower seat cushion hooks to the mounting holes. Fold the seat back cushion up until it latches into position, then reinstall the seat back cushion retaining bolts.

    14

    Set the lower seat cushion into position and engage the rear latches with the retaining hooks on the back of the seat. Fold the seat down and reinstall the seats retaining bolts. Reinstall the tires and torque the lug nuts to lug nuts to 65 foot-pounds, plus or minus 7 foot-pounds. Lower the vehicle back to the ground, then test drive it to ensure that the sensors operate properly.


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