Weird ABS problem that stumps dealer

Discussion in 'Trucks [ Eighteen Wheelers ]' started by 4play, Nov 11, 2011.

  1. 4play

    4play Light Load Member

    90
    12
    Nov 11, 2011
    Edmonton
    0
    Maybe someone on here has an idea, ok, I Have a 2012 VNL780 with the Ishift and d13 engine and since Brand new after driving a while the abs and traction control light would come on the same time, to be more specific after driving it almost exactly 8km at above 90km/h. If I shut the truck off and re start it the lights are off but exactly 8km down the highway at 90 or above the light trips again like clockwork so it was at the dealership they pulled a couple of codes from the right front wheel sensor said the tone ring was good, they replaced the abs sensor, no difference at all, they swapped out the Brake control module, no difference and they checked the wire harness, it's good. plus on top of it all they re flashed the computer nothing they did made no difference at all anyone on here have any ideas what may be going on here?
     
  2. Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.

  3. fortycalglock

    fortycalglock Road Train Member

    5,971
    6,162
    Jun 25, 2011
    Tourist Town, FL
    0
    What were the codes? If the codes are for the right front wheel and they've replaced the sensor and checked the harness, time to replace the tone ring, or most likely the whole hub if they're like mine.
     
  4. 4play

    4play Light Load Member

    90
    12
    Nov 11, 2011
    Edmonton
    0
    oh i'm not 100% sure but one was an air gap code, but it has been doing this since the truck was brand new 50km on the clock, tone ring is good, it's just weird that the light triggers at the same 8km every time. why the whole hub? built into the tone ring?
     
  5. Sparkz

    Sparkz Light Load Member

    76
    15
    Jul 10, 2011
    New Zealand
    0
    Does the tone wheel run true?
    Is the wheel bearing preload set correctly?
    Does the sensor go out of adjustment?
    Have they checked the scope pattern from both front sensors at the ECU?
    Have they tried running a temporary twisted pair from the sensor to the ECU?
     
  6. CondoCruiser

    CondoCruiser The Legend

    19,726
    18,699
    Apr 18, 2010
    Tennessee
    0
    If there was an ABS problem, it wouldn't be setting off the traction control light at the same time. Especially a front wheel.

    There's a common denominator of the two circuits somewhere, whether it's the ECU, a wire short or instrument panel.

    Don't think all dealers are experts either. I been to some that were clueless of the problem and go to the next and they find it right away. Alot has to do with the technicians expertise.

    I would try a different dealer.
     
  7. Pablo-UA

    Pablo-UA Road Train Member

    7,604
    1,618
    Oct 11, 2010
    Borispol, Ukraine
    0
    first of all! what a code in MID 136 PID FMI format?

    what brake ECU (Wabco ABS-E, E+, Knorr/Bendix, ore EBS with ESP)?

    and a good advice - check bearing for play and tires for ballancing, size, wear. Rattle may cause ABS/EBS throw bad polering codes.
     
  8. Heavyd

    Heavyd Road Train Member

    7,227
    5,415
    Feb 4, 2009
    0
    I usually don't see both the ABS and Traction Control light both come on with a sensor failure or modulator failure. I do see both come on with a traction control problem or communication problem. Having this phenomena happen at a certain distance interval is very interesting. I have never of it. The abs ECU is one of many electronic devices connected together through a communication data link. I have see several times where another component is faulty and causing some havoc for other devices. Bendix ABS ECU's are too sensitive to very minor electrical inconsistencies. Their fault trigging tolerances are too low and they set codes very easily. If your truck has a Qualcom or other satellite communication try to disconnect it. Also if your truck has a data display for engine information, or vehicle navigation, compass or anything like this they may share the same data link with the ABS ECU. Try to disconnect these devices one by one if you can. Also try to disconnect the alternator positive lead at the alternator and see if the problem says or goes away to determine if the problem is being cause by something else.
     
  9. Pablo-UA

    Pablo-UA Road Train Member

    7,604
    1,618
    Oct 11, 2010
    Borispol, Ukraine
    0
    new Wabco ABS units (really made in Wrozlaw, PL) are not interferece sencetive, so bad alternator cant cause this kind of problem. But bad bearing can! If pole ring was tested and it is ok, may be... bearing play, kingpin play, disballanced tire....

    MID 136 saves bad speed signal code if the signal is really bad.

    This truck is relativelly new, so Wabco S+ sensors are used. Better magnet, better insolation! The only electrical problem I belive is bad extention wire. It is cheap thing. I use to change it with sensor.
     
  10. Heavyd

    Heavyd Road Train Member

    7,227
    5,415
    Feb 4, 2009
    0
    Yah, we don't see too many Wabco systems around here anymore. I think Volvos use something different from that too. I wonder if something mechanical is the issue the fault is occurring only every 8 km? This may be how long it takes for the code to be triggered so faults don't get logged for minor glitches I guess.
     
  11. Pablo-UA

    Pablo-UA Road Train Member

    7,604
    1,618
    Oct 11, 2010
    Borispol, Ukraine
    0
    do you know how to identify control unit?
     
  • Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.

  • Draft saved Draft deleted