A restoration of ABS system operability by your own is possible only if its defects are caused by breakdown of wheel speed sensors. They operate in aggressive conditions, are apt to effect of moisture, gritting salt, mechanical damages, fouling and are most vulnerable elements of the ABS system.

Sometimes, for restoration of sensor operability, it is sufficient to clean the sensitive element from accumulated dirt. In case of more serious damages, components are to be replaced. It is not recommended to repair the control unit or back pump of ABS by your own efforts: this process requires specific skills and it should be entrusted to professionals.

Operability of the ABS sensor can be checked with the help of a multimeter and repair cables with special sockets. To do this, you need to perform the next actions:

1. Lift the car from the needed side and fix its position with the help of pillars or lift.
2. Demount the wheel, if necessary.
3. Remove the protective cover from the ABS module and remove the sensor socket.
4. Connect the repair cable to the tester, and then the sensor.
5. Measure resistance and compare with data, noted in technical documentation of the vehicle. Operability of the components is indicated by resistance equal to 650-1350 Ohm.
6. Rotate the wheel with 1 rotation per second speed. The multimeter should indicate voltage in range of 0.25-1.20V.

Search for tutorial videos for more details about check performing.

In order to remove the ABS sensor, you need to lift the car with the help of a jack, dismantle the wheel, unscrew bolts which fasten a caliper to a hub, and then fix its position using a wire. Then, you need to demount the braking disc and pads, to gain access to sensor fastening location.

The component and its retaining bolt should be cleaned from dirt and wiped dry. To remove stuck fastenings, use the special product for rust removal, for example, WD-40 or braking liquid.

Carefully grasp the metal housing with pliers, and remove it slowly tilting. Disconnect the socket of the components from the car electric system.

In many cars it is located under a rear seat. Push out the wire and the rubber seal, then, disconnect it from the body bottom. In some vehicles, the ABS system sensor can be removed without demounting of the wheel and braking system elements, because its fastenings are mounted outside of all mechanisms.