Braking, ABS Related, Suspension

Braking, ABS Related, Suspension


Various topics on ABS braking and Suspension issues:


  1. Wheel Speed Sensor Faults

    Check sensor continuity across the two wires with an ohmmeter.  Should check 1200 to 1800 Ohms if good.  Open circuit or very low resistance is a failed sensor.

    Wheel speed sensor is intended to be installed directly against the tooth wheel with no air gap.  The sensor can tolerate some small air gap (<0,5mm if I remember right) caused by the hub run out.  If you have a wheel speed sensor fault I recommend you check wheel bearing end play as well, should be 0.01 to 0.05 inch unless fitted with a unit bearing or preset.  Dirt and brake dust can accumlate on the tooth ring and cause the sensor to move away from the ring as noted by some of the posters.

    The output of the wheel speed sensor can easily be checked with a voltmeter.  Spinning the wheel should generate a voltage.  Simple as that.

    On 6x4's, which axle is the fault?  One system refers to the axles as 1,2,3 and the other system refers to the axles as 1,3,2.  If the sensor looks good but the fault is still there* then try the other axle to be sure.

    * The vehicle has to be driven to make sure the fault is gone. *

  2. Operation of a Vehicle with Active ABS Fault and Light:

    There is no out of service criteria for operating a vehicle with an ABS fault.  There should be.  However, the ABS system is relatively fail safe, in that ABS failures do not "normally" cause loss of braking performance.  Clearly an ABS fault light means the system has failed and the benefits of ABS will not be functional.

  3. Spring Cans

    The spring cans hold the very powerful springs that apply the brakes of the rear wheels when air pressure is removed, commonly called the parking brakes.  At the best, these springs can hurt you badly if they get released from within the can.  Only the most experienced mechanic should attempt to work with the spring cans.  There are special tools that are needed.  Read the thread below.

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