Peugeot 406 ABS problem

Discussion in 'Peugeot 406' started by Marc Barbour, Sep 24, 2006.

  1. Marc Barbour

    Marc Barbour Guest

    I have a 2000 model Peugeot 406 HDi that I purchased earlier in the
    summer. There is an intermittent fault with the braking system that
    causes the ABS to operate when braking gently at slow speeds, typically
    less than 20 mph, which results in pulsing felt through the brake pedal.
    This is typically annoying but there have been a couple of times when
    stopping on a dry road that the car has felt like it's braking on ice
    (with the ABS pumping way) and considerable pedal pressure has had to be
    used to stop the car before it hits the vehicle in front. The ABS works
    fine if I try and force it to engage when braking heavily from moderate
    to high speeds.



    I have tried a couple of things to cure the problem including bleeding
    the brakes, replacing the front discs and pads and cleaning the front
    sensors and toothed rings. When replacing the discs I noticed that the
    toothed ring that the ABS sensor reads on the OSF could be turned around
    the driveshaft and would also slide along it (I estimate about 10 lbs ft
    of torque was need to turn it around the circumference of the
    driveshaft). It is also split like a circlip that results in the teeth
    on either side of the split being further away from each other than the
    corresponding teeth on the rest of the ring. I imagined that this
    toothed ring would be an integral part of the driveshaft rather than the
    separate, relatively loose part that it is. I am wondering whether this
    is as the car was manufactured or whether in the past someone has bodged
    replacing the driveshafts. The toothed ring on the NSF is also split but
    takes a bit more effort to move.



    Can anyone confirm whether the toothed ring and driveshaft should be
    like described? Any ideas where else could be causing the fault. I have
    now pulled the ABS fuse for greater peace of mind whilst driving but
    would like to get this sorted before winter sets in.



    TIA



    Marc
     
    Marc Barbour, Sep 24, 2006
    #1
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  2. Your problem is most likely to come from either an incorrect wheel
    speed being recieved - i.e. the sensor not reading the disk correctly,
    damaged wires or faulty control unit.

    I would suspect the disks at the moment - if your local scrap yard has
    a scrap 406 you could look at that.

    I wouldn't expect it to be mechanical - brake fluid, pads, brake disks
    etc.

    I would be surprised if an ABS warning light didn't come on though if
    one of the wheel speed sensors was faulty.
     
    405 TD Estate, Oct 2, 2006
    #2
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  3. Hi Marc

    My money is on the toothed rings. They should only move with the axle and
    you should not be able to move them independently. The ABS control unit
    reads whether a wheel is locking up, and reacts accordingly, by counting the
    teeth passing by the wheel sensor. Obviously, if the toothed ring goes
    slower than the rest of the axle, the system adjusts the brakes incorrectly.
    Even if the ring moves at the same speed as the axle, the margin of error
    due to the split ring (circlip) is enough to confuse the system. It relies
    on equal distance between the teeth.
    If your car is like my 605, you must replace the outer CV joint complete
    with a new ring.

    Good luck, and let us know how you solve the problem.
     
    Ívar Pétur Guðnason, Oct 2, 2006
    #3
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