Diagnosing ABS Fault

  1. Saxperience Hardcore! Joined: Oct 2005 Aycliffe Posts: 32205 Saxo VTS
    #1
    Hi all,

    The ABS light has appeared on the dash so it's time to whack out the multimeter and start probing about. However, I'm not sure what could be at fault or what to expect for resistances across the sensors - Does anyone know this information?

    ORRR... does anyone know what the common faults are on the ABS System so I can use that as a starting point?

    Cheers!

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  2. Saxperience Addict Joined: Jul 2005 Solihull / Bournemouth Posts: 14233 2015 Lapiz Blue Golf R
    #2
    check resistance across the sensors, and then compare them to each other.

    I've got the Saxo fault finding manuals here so will have a quick look and let you know if they say anything helpful
  3. Saxperience Hardcore! Joined: Oct 2005 Aycliffe Posts: 32205 Saxo VTS
    #3
    Ross you're a ledge, cheers!

    I've found a wiring plug diagram for the ABS, so it's easy enough to diagnose if there is a fault with the sensors... it just the resistances which seem a bit speculative.
  4. Saxperience Addict Joined: Jul 2005 Solihull / Bournemouth Posts: 14233 2015 Lapiz Blue Golf R
    #4
    Mate I've got the Citroen manual for diagnosing the ABS system on a Saxo, will have a quick scan and summarise it on here - it looks to be for a mk1 one the principles should be the same
  5. Saxperience Addict Joined: Jul 2005 Solihull / Bournemouth Posts: 14233 2015 Lapiz Blue Golf R
    #5
    It basically says:

    - either the ABS unit has a fault itself (can imagine unlikely)

    - or one of the wheel sensors is at fault.
    > check the fixing and state of the sensor and teeth on the driveshaft/hub
    > With the sensor disconnected put a mulitmeter across it, value of sensor should be around 1.1Kohms
    > With the sensor disconnected check insulation from earth > 20Mohms (not sure what this means tbh)

    > Somehow, with the sensor plugged in, check operation of the sensor by rotating the wheel - it should be > 0.1volt but obviously varies with speed.

    Hope this helps mate
  6. Saxperience Hardcore! Joined: Oct 2005 Aycliffe Posts: 32205 Saxo VTS
    #6
    Quote:
    Originally Posted by raunchz View Post
    It basically says:

    - either the ABS unit has a fault itself (can imagine unlikely)

    - or one of the wheel sensors is at fault.
    > check the fixing and state of the sensor and teeth on the driveshaft/hub
    > With the sensor disconnected put a mulitmeter across it, value of sensor should be around 1.1Kohms
    Brill that's what I was looking for.


    Quote:
    Originally Posted by raunchz View Post
    > With the sensor disconnected check insulation from earth > 20Mohms (not sure what this means tbh)
    I'm not sure either. I guess this is checking that sensor hasn't shorted against its fixing?

    Quote:
    Originally Posted by raunchz View Post
    > Somehow, with the sensor plugged in, check operation of the sensor by rotating the wheel - it should be > 0.1volt but obviously varies with speed.
    No idea how I'll do that one but I suspect it'll be a sensor!

    Thanks man,

    Oh and I need this Citroen Manual you speakth
  7. Saxperience Post Whore Joined: Apr 2007 Posts: 6640 Integra DC5R & VTS
    #7
    Pull that connector from behind the battery and check the relevant pins. 1100 ohms is a working sensor, 0 is a dead sensor.
  8. Established Member Joined: Jun 2009 Southend, essex Posts: 2079 1999 mk2 VTS EP3 2004 civic type r
    #8
    As lee said, did this last week its nice and simple
    1 user thanked this post:
  9. Saxperience Hardcore! Joined: Mar 2005 Pompey/Darlo Posts: 31546 MK1 - 1.1 Animal
    #9
    look on ssc, search for it, iron bruce or something put up a guide

    bobs your uncle you will find it

    then drive over to mine to say hello