1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  2. Welcome To LandyZone!

    LandyZone is the biggest Land Rover forum on the net. We have plenty of very knowledgable members so if you have any questions about your Land Rover or just want to connect with other Landy owners, you're in the right place.

    Registering is free and easy just click here, we hope to see you on the forums soon!

P38A Front Wheel ABS Speed sensors

Discussion in 'Range Rover' started by awkwardbob, Jan 29, 2021.

< Previous Thread | Next Thread >
  1. awkwardbob

    awkwardbob Well-Known Member

    Joined:
    Aug 3, 2020
    Posts:
    502
    Likes Received:
    260
    Location:
    Glasgow
    Hi,
    I’m having a wee issue with my ABS.
    I’ve the yellow warning lamp on the dash but no error message.

    Nanocom reports no ABS faults but I did notice that, while the rear wheel
    Sensors register road speed correctly, the fronts resolutely remain at 0mph.

    Is this likely the source of the problem ? Ie. As part of its check, the system isn’t registering the road speed necessary to reset the warning indicator.
    If so, is there a way of adjusting these ? (Where physically are they and what do they look like ?)
    As it’s both front wheels, could it be something electrical like a fuse or relay common to both ?

    thanks in advance for any help
    Or advice !

    Bob
     
  2. wammers

    wammers No longer with us, RIP Donater

    Joined:
    Oct 19, 2008
    Posts:
    58,171
    Likes Received:
    11,667
    Location:
    Preston Lancs.
    Could be wear in front wheel bearings causing working gap to go out of range. Push both sensors in until the are in contact with rotor and see what you get.
     
    awkwardbob likes this.
  3. awkwardbob

    awkwardbob Well-Known Member

    Joined:
    Aug 3, 2020
    Posts:
    502
    Likes Received:
    260
    Location:
    Glasgow
    I’ll have a go at that.
    I’m just a wee bit suspicious as the issue only appeared after I had the dash out to re-bulb it, and odd that it’s both front sensors..

    -that’s assuming, of course, that the yellow
    ABS light hadn’t blown (or been removed) and the faults been there all along !
     
  4. wammers

    wammers No longer with us, RIP Donater

    Joined:
    Oct 19, 2008
    Posts:
    58,171
    Likes Received:
    11,667
    Location:
    Preston Lancs.
    ABS lamp should come with ignition flicker then stay on until road speed passes 5 MPH.
     
  5. awkwardbob

    awkwardbob Well-Known Member

    Joined:
    Aug 3, 2020
    Posts:
    502
    Likes Received:
    260
    Location:
    Glasgow
    Yes, it does that now but stays on.
    No fault codes in the ABS nor anything in the info centre so suspect it may be that it’s not registering speed.
    Can’t remember if that bulb worked or not before replacement, I only remember the red handbrake one (I think)
     
  6. wammers

    wammers No longer with us, RIP Donater

    Joined:
    Oct 19, 2008
    Posts:
    58,171
    Likes Received:
    11,667
    Location:
    Preston Lancs.
    They won't register speed if the gaps are too large
     
  7. Grrrrrr

    Grrrrrr Technician, Bodgit & Scarper Ltd Full Member

    Joined:
    Jul 8, 2012
    Posts:
    17,293
    Likes Received:
    7,440
    Location:
    Buckinghamshire, UK. ('95 DT)
    What year car? Does it have 4W TC?

    @wammers can you swap sensors front to back? Thinking he could see if the fault moves and check continuity and resistance at the same time. Sure someone posted expected resistance on here somewhere.
     
  8. wammers

    wammers No longer with us, RIP Donater

    Joined:
    Oct 19, 2008
    Posts:
    58,171
    Likes Received:
    11,667
    Location:
    Preston Lancs.
    No. Early ones only go in the one position. Later ones can be swapped side to side but not front to rear.
     
    Grrrrrr likes this.
  9. Karlos the jackal

    Karlos the jackal Well-Known Member

    Joined:
    Nov 24, 2019
    Posts:
    409
    Likes Received:
    152
    Location:
    Norfolk
    isn't it 100 -1000ohms? for the continuity resistance
     
  10. awkwardbob

    awkwardbob Well-Known Member

    Joined:
    Aug 3, 2020
    Posts:
    502
    Likes Received:
    260
    Location:
    Glasgow
    It’s a ‘97 Gems 4.6, I’ll have a rummage around tomorrow.
    You reckon the resistance from the sensor going to the ECU should be 100-1000 ohms ?
    I can have a check of that if I can find where the connector lives !
     
  11. wammers

    wammers No longer with us, RIP Donater

    Joined:
    Oct 19, 2008
    Posts:
    58,171
    Likes Received:
    11,667
    Location:
    Preston Lancs.
    Was talking EAS sensors there silly me. Suppose you can swap around speed sensors just different wire lengths front to rear. You need five volts to the sensor this pulses as wheel rotates giving the signal to the ECU.
     
    Grrrrrr likes this.
  12. awkwardbob

    awkwardbob Well-Known Member

    Joined:
    Aug 3, 2020
    Posts:
    502
    Likes Received:
    260
    Location:
    Glasgow
    Is that 5V feed fused anywhere ?
    It just seems a bit odd to lose both front sensors simultaneously, -or maybe a less than fully healthy battery ? -that said Nanocom reads 16V with the engine running
     
  13. tomcat59alan

    tomcat59alan Well-Known Member

    Joined:
    Apr 3, 2011
    Posts:
    18,607
    Likes Received:
    12,603
    Location:
    wirral and triquivijate
    16v seems a bit high to me.
     
    kermit_rr likes this.
  14. wammers

    wammers No longer with us, RIP Donater

    Joined:
    Oct 19, 2008
    Posts:
    58,171
    Likes Received:
    11,667
    Location:
    Preston Lancs.
    The voltage to the sensors is five. Check them for continuity and for voltage.
     
  15. kds

    kds Well-Known Member

    Joined:
    Nov 10, 2008
    Posts:
    2,107
    Likes Received:
    937
    Location:
    old,ugly, tired in Lincoln.
    16 volts will frighten some of the ecu to death.
     
    kermit_rr likes this.
  16. awkwardbob

    awkwardbob Well-Known Member

    Joined:
    Aug 3, 2020
    Posts:
    502
    Likes Received:
    260
    Location:
    Glasgow
    I meant 16V from the alternator / battery not at the sensors -sorry, it’s been a looong day
     
  17. romanrob

    romanrob Well-Known Member

    Joined:
    Jan 19, 2020
    Posts:
    457
    Likes Received:
    227
    Location:
    SW London
    The 16volt read on nano is a known issue (actually i believe it's not nano but certain becm versions) ignore the 16v and measure yourself...
     
    Last edited: Jan 31, 2021
  18. romanrob

    romanrob Well-Known Member

    Joined:
    Jan 19, 2020
    Posts:
    457
    Likes Received:
    227
    Location:
    SW London
    Remove the abs sensors and boots and clean the ****e off them, retrieve the metal cages carefully clean those up too. Lightly grease and replace. Dont hammer them, just a firm push fit... Before you replace them, check the end of the sensor is smooth, with a small convex bump in the middle...which indicates they have not been damaged previously
     
    awkwardbob likes this.
  19. romanrob

    romanrob Well-Known Member

    Joined:
    Jan 19, 2020
    Posts:
    457
    Likes Received:
    227
    Location:
    SW London
    Rl2, f24 and f27 if you want to eliminate those...
     
    awkwardbob likes this.
  20. wil2813

    wil2813 Well-Known Member

    Joined:
    Feb 14, 2010
    Posts:
    2,324
    Likes Received:
    98
    Location:
    the bit inbetween j10-j11 m6,west mids.
    Hi alan
     
< Previous Thread | Next Thread >