348 abs judder | FerrariChat

348 abs judder

Discussion in 'Technical Q&A' started by Lea348, May 9, 2020.

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  1. Lea348

    Lea348 Rookie

    Sep 16, 2011
    2
    Hi everyone my 1993 348 ts has started chattering is the best way I can put it under minimal brake pedal pressure not always but getting gradually more and more, brakes seem fine when it is working well it does throw a warning light on now and then but does go off on its own.

    any pointers would great

    cheers Lea
     
  2. fatbillybob

    fatbillybob Two Time F1 World Champ
    Consultant Owner

    Aug 10, 2002
    29,272
    socal
    Let's be sure of the diagnosis. Do you have an ABS problem of a judder problem. Those 2 are not related. Like many of these kinds of threads not enough info is revealed or information trickles in that changes the direction of the solution.
     
  3. Lea348

    Lea348 Rookie

    Sep 16, 2011
    2
    No definitely an abs issue, it’s as if the abs is coming on when not needed and sometimes even before you move as soon as you put your foot on the pedal it pushes back slightly but not always
     
  4. Qavion

    Qavion F1 World Champ
    Silver Subscribed

    Feb 20, 2015
    14,534
    Sydney
    Full Name:
    Ian Riddell
    #4 Qavion, May 9, 2020
    Last edited: May 9, 2020
    Do you know the test procedure for the ABS system? Basically, it involves putting a 5 or 10 amp fuse in the empty test slot, putting the ignition key to "RUN" and looking at the ABS light.

    The procedure is described in detail in the workshop manual if you have one.
     
  5. kryten2001

    kryten2001 Formula 3

    That procedure will return a fault, if there is one.

    My best guess on this would be your ABS wheel sensors, or at least that's where I'd start. You want to check that one of them isn't returning an erroneous reading which is throwing the ABS unit off.

    The sensors are pretty basic (technically) but they can get thrown off by grease/dirt or by breakage of the cable or a bad/loose connector joint.

    To do this is not a massively difficult task. You just need to spin the wheel and read the readings on the appropriate input pin(s) on the ABS connector cable. You'll have the TEVES unit on there.. I know there's some good videos on youtube that deal with this.
     
  6. tracktoys

    tracktoys Rookie

    Feb 5, 2017
    18
    Wales UK
    sensors are magnetic and can sometimes pick up something metal (especially if you've had the wheels off for any reason), the abs module will think the wheel is locked as ts getting a continuous signal and kick the pump in
     
    Qavion likes this.

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