What are some basic steps to diagnosing ABS brake warning lights on Taurus - Sable?

ABS, anti-lock brake systems are actually pretty basic:
  • Control module
  • Wheel sensor / 'exciter' ring (toothed gear integrated into end of axle shaft)
Diagnostics
  • Examine each wheel for physical problems
  • **
    • Mud & debris on the ring that could interfere with the sensor
    • Wiring - broken, frayed, corroded
    • Wiring connector - disconnected, corroded

  • Trouble codes
  • **
    • requires specialized scan tool (about $200)

    • As with engine codes, will provide more detailed information for diagnostics - such as a recurring code to a specific wheel as in my case.

    • Appears that most places charge to have codes read - I paid $45 at my favorite tire shop. Dealers, brakes shops, tire shops, some auto parts offer ABS scan / code retrieval
Repair
  • Wheel sensor

    • Sensor mounts into the back side of the steering knuckle with one small bolt. Can be stuck in the casting and take some effort to remove in one piece (in case you're trying to salvage it). Be patient and have good penetrating oil on hand.

    • Trace wiring - the front connectors are typically up behind the plastic wheel well liner for protection from the road elements - lots of sheet metal screws & more penetrating oil

    • Individual sensors range in price from about $45 and up

  • Control module
  • **
    • Not repairable and expensive (that's about all I know)

  • Bleeding the system

    • ABS systems are particularly sensitive to air in the lines - the control module gets upset by the presence of anything but fluid.

    • According to Chiltons procedure write-up, the ABS scanner needs to be used during bleeding process

    • The bleeding sequence goes Rt Ft, Lf Ft, Lf R, Rt R

    • sounds like it is a complete flushing of fluid - have a few jugs of fluid on hand


See "Related Questions" below for more ABS information