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P38A Abs sensors!! Fixed.

Discussion in 'Range Rover' started by Mark Piercy, Feb 8, 2018.

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  1. Mark Piercy

    Mark Piercy Well-Known Member

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    1999, 2.5tdi Auto.
    Greetings one and all, question for the masses.
    Would anybody by chance know the resistance reading of a good known abs sensor?
    Three amigos and traction faults arrived this morning....
    Unfortunately without the help of the nano' I can't diagnose these electronically.
    What would my target resistance be please?
    Thank you one and all;):)
     
  2. biketeacherdave

    biketeacherdave Well-Known Member

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    Iv got one in the garage I'll go see if I can find it and check
     
  3. Mark Piercy

    Mark Piercy Well-Known Member

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    Your a star, thank you! The rear two are recent, clean and white on em, the front two are a little less recent....
     
  4. biketeacherdave

    biketeacherdave Well-Known Member

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    1.3 k ohms
     
  5. Mark Piercy

    Mark Piercy Well-Known Member

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    Brilliant. Tomorrows job!! Meter at the ready!!! :cool:;)
    Thank you very much fellow bus driver;)
     
  6. Mark Piercy

    Mark Piercy Well-Known Member

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    Both the fronts read around 880 ohms.. the rears I couldn't do due to other things going on...but I'm not ruling them out just yet even though they are recent...o_O
     
  7. wammers

    wammers STILL BREATHING. Donater

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    As long as they have resistance and are not open circuit or closed circuit they should be fine. They are fed with 5 volts the fluctuation of that voltage as they pass over the reluctor ring peaks and troughs sends a pulse to the ECU 8,000 pulses per mile if a remember correctly.
     
  8. Mark Piercy

    Mark Piercy Well-Known Member

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    Thank you, next move is to check the rears when my garage is empty and hopefully one may have failed... If not I'm in the poop... The abs pump function and charges as it always has done for the last year and a half of ownership, so I know that's doing its job, no drop in performance from the brakes either.
    Checked all the fuses in the box, all in good shape, clean no smells and no dust build up either. (Just to rule out)...
    Watch this space..o_O;)
    Thanks for helping me.;):)
     
  9. wammers

    wammers STILL BREATHING. Donater

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    When fitted they have to be pushed in until they contact the reluctor ring. Gap is set when reluctor ring rotates. Sometimes a slightly worn hub bearing pushes them out until they begin to lose signal. That would certainly cause what you have.
     
  10. Mark Piercy

    Mark Piercy Well-Known Member

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    Thanks wammers, checked all four for fitment and resistance.
    Purely by coincidence....
    Turned the key, let it charge the brakes then turned the key off.
    Turned it and started it up. No warning..
    Touched the brakes and bingo!!!!
    Three little buggers and a beep?
    The pump is behaving as it should. My thoughts are the sphere..
    I know it's always been getting long in the tooth to charge and I'm wondering if it has reached its end???
     
  11. Grrrrrr

    Grrrrrr Well-Known Member

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    If the pump runs after every other press of the brake pedal then it is definitely duff. Are you sure there is no air in the system?
     
  12. Mark Piercy

    Mark Piercy Well-Known Member

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    Cheers grrrrrrr,
    Absolutely sure buddy. All bled to the book! I've also checked the connection to the pump pressure and pump feed electronic plugs. All good and clean.
     
  13. brianp38dse

    brianp38dse Well-Known Member

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    Have a check of the brake peddle switch, take it out pull out the plunger hold brake peddle down put switch back and let peddle up to set it, may well sort out fault, it did on mine.
     
  14. Mark Piercy

    Mark Piercy Well-Known Member

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    thanks brian, did consider that. but i figured since i have working brake lights and functioning cruise control it should be ok?
    that is a must on your advice. good call .;)
     
  15. tarphenry

    tarphenry Well-Known Member

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    mine was the switch and I had good brakes and lights
     
  16. Mark Piercy

    Mark Piercy Well-Known Member

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    next port of call! cheers.;)
     
  17. Mark Piercy

    Mark Piercy Well-Known Member

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    Just a thought on the pedal, but not to rule it out..
    For example, if I go out now and turn the key after it's been sat all night. It will charge and find fault immediately,
    If I turn it off straight away and then turn it back on again, fully charged there is no fault until I tap the brake pedal and compromise the pressure stored in the system.
    I'll check the pedal switch, by all means but as I say the second time I turn the key there are no faults?
    Thanks for all your help;)
     
  18. brianp38dse

    brianp38dse Well-Known Member

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    Ok that sounds different.
     
  19. Grrrrrr

    Grrrrrr Well-Known Member

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    Does sound like pressure or air in there. But if the accumulator was bust I'd expect the pump to run every push of the pedal or every other push.
     
  20. wammers

    wammers STILL BREATHING. Donater

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    When you switch on TC lamp should be on and pump should run. When system reaches minimum working pressure TC lamp should go out, but pump will continue to run until max working pressure is reached then pump will switch off. It's not the pedal switch you need to look at but the dual pressure switch on the pump.Maybe the accumulator has leaked and put some of it's nitrogen charge into the system.
     
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