ABS light on, MOT fail ?

Discussion in 'Tech/Mech General' started by jockaneezer, Feb 28, 2015.

  1. jockaneezer

    jockaneezer Funster

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    The ABS light on my 05 Renault Master came on and off a couple of times just after going through some big puddles. It's now on all the time. I had a look at the sensors and their connections for the front wheels yesterday and wire brushed the rotors, no better. Obviously I need to check the back two next. My mot is due next month, will this be a fail ?
    Is it worth taking it to a main dealer to get the fault codes read, would it show anything up ? I don't think those bluetooth code readers you get on ebay do braking systems, only engine codes ? I'd like to do any repairs myself, within reason.
    TIA, Graeme.
     
  2. karl c

    karl c Funster

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    try taking the batt of for 10 mins see if it clears the code first.
     
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  3. Tootles

    Tootles Funster

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    I have heard that it is now a fail.......However, if it's disconnected for the test, then they cant fail it, under the 'not required, but if connected must be working' rules.
     
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  4. CHRI$

    CHRI$ Funster

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    a code reader not only does engine codes it will read all codes that are stored on the ecu and will will show which wheel censor is faulty,simply get the code and google it,also check the reluctor rings for crack's as a cracked reluctor ring will show as a faulty censor.
     
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  5. ivorantony

    ivorantony Funster

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    Yep if the abs light is on it will fail, do exactly what you are doing and clean the sensor/ check the leads and connectors plus clean the rotors,
    You shouldn't need. Main dealer to read the codes any decent size garage should be able too and pinpoint the sensor that's gone down if your cleaning doesn't meet with success,
    Taking battery off line wouldnt clear a abs fault code
     
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  6. Fireman Sam

    Fireman Sam Funster

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    A fail! Is that true? My ABS hasn’t worked for years and the car always sailed through the test. I suppose that I’ll have to have the damn thing fixed now.

    O bother!
     
  7. WillH

    WillH Funster

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    My van failed on the ABS light being illuminated a few years ago. Fault was intermittent but eventually traced to a wire rubbing on the loom behind the nearside headlamp, this is on an X250 chassis.
     
  8. John Laidler

    John Laidler Funster

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    ABS units, or at least some of them, can be repaired, if that is traced to the fault. It will cost the odd hundred or two but a new unit could be a £1K or more unless you can get one from a breakers.
     
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  9. ivorantony

    ivorantony Funster

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    Unfortunately some of the latest ABS ECU are coded to the main ECU to gives us things we always needed but didn't know,
    Like Traction control/stability control and tyres being under inflated so you cannot just pop on one from the breakers and expect it to work,
    But Devon beekeeper has the right idea about prices!
     
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  10. tonyidle

    tonyidle Funster

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    The MoT checks for correct function of the ABS warning light. It must illuminate for few seconds when the ignition switch is turned on then go out.
     
  11. Zains Pops

    Zains Pops Funster

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    Our 1998 Honda Civic went to the great car park in the sky due to an ABS lamp issue. It had come on and off for a few years, and I managed to get a a couple of MOT's in the off stage. However it then moved to permenantly on and that led to a fail. The fix cost was more than the car was worth so we decided it had to go. A great shame as in all other areas it was still a great car that went well.
     
  12. jockaneezer

    jockaneezer Funster

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    Thanks for all the replies/suggestions. Still got a couple of things to check out but am aching from rolling about under it yesterday. Going to have to get myself a 3 ton trolley jack to make life easier (y)
     
  13. Larby

    Larby Funster

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  14. Wickolad

    Wickolad Funster

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    Hi, you say it started after going through some puddles, this could indicate that its moisture in the electrics thats the problem. If youve cleaned the sensors and rotors and still have problem, check the plug connectors, usually just inside engine compartment near to wheelarch, trace wires from sensor, through inner arch to engine bay, 2 wire plug connection will be about 10" higher than entry point. Seperate the plug connectors, clean and spray with WD, disperses water/moisture and refit. This may well sort it.
    I had same problem with a vehicle, intermittent abs light and found it to be the plud connector bad connection that didnt like wet conditions. (y)
     
  15. olley

    olley Funster

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    As has been said the MOT test know includes looking for dashboard lights that should light, and its a failure if they don't. So no good removing the bulb for one that stays on.

    Ian
     
  16. Jonkil

    Jonkil Funster

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    Wheel sensor most likely.
    Have it read, and not all readers will do it.... EOBD readers only WONT read it.
    Been a failure here in Ireland for about 5 years and it's a regular repair in the workshops.
     
  17. Peter A Forbes

    Peter A Forbes Funster

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    Land Rover Discovery owners do this all the time!

    The main faults are:

    Loss of signal from any wheel sensor
    Incorrect signal from any wheel sensor
    Signals not matching.
    Shuttle valve switches in the ABS Modulator
    Wheel bearing failed giving too much wheel play and thus the gap between the sensor and toothed ring varies.

    Most cars have similar systems, albeit you cannot swap modulators between different cars, or rarely anyway.

    Sensors are a magnet with a coil wound round its body. Rotating a toothed ring (reluctor ring) past the end of the magnet induces a signal in the coil which is passed to the ABS ECU.

    Of the regular faults, wheel bearing play and sensors with rust particles across their faces are the most common.

    Sensors can be removed, cleaned and refitted.

    Broken sensor cables seem to happen a lot, not sure why.

    Shuttle valve switches are in the ABS modulator valve block. Land Rover sell a kit for £40 or so which is a new set of switches and their mounting plate, don't know about other makes.

    Water in the connections to the sensors will short out the signal, which is pretty weak anyway.

    I'd look at wheel bearings and sensors first.

    Peter
     
  18. pappajohn

    pappajohn Funster Life Member

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    Only if you part with megabucks Chris.

    £30 OBD readers only do engine fault codes.
     
  19. pappajohn

    pappajohn Funster Life Member

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    Depends on the manufature year.
    some lights are allowed...my 2007 Chrysler had the tyre pressure light on, not a fail due to year.
    i believe its post 2012 vehicles that will fail on any light.
    ABS will be a fail regardless of year.
     
  20. pappajohn

    pappajohn Funster Life Member

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    And some heavy axle stands i hope.

    NEVER rely on a jack alone...even a new one.
     
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