Forum Discussion

danimal53's avatar
danimal53
Explorer
Sep 20, 2016

speed sensor malfunction while towing?

I've been recently having a strange problem, and after researching I think I know the cause (sort of).

My TV (Jeep Liberty) has known issues with ESC turning off, which then disables 4WD. Multiple error lights go on on the dash, ESC and SERV 4WD. This is apparently related to the ABS speed sensors, one is probably broken. The odd thing, these lights go on and all these errors occur for me only when towing (coachmen clipper 17bh, with E2 wdh). After a couple days not towing, all the lights are off and everything is back to normal on the Jeep.

anyone ever encounter something like this? is trailer sway triggering ESC, and making it go haywire?
  • danimal53's avatar
    danimal53
    Explorer
    Sep 21, 2016
    BenK wrote:
    Most are Hall Effect sensors and they have a permanent magnet in there...suggest
    taking a look to see if it is overloaded with iron dust most pickup from the
    street

    Brush or wipe off that dust to see if that cures the problem

    {edit}...ops...thinking of ABS sensors...most likely will not apply
    to a speedo sensor, as they normally are inside something...like the tranny, etc


    no i think we're talking about the same thing, ABS wheel speed sensors. I'm going to take a good look this weekend, take of the wheels etc and see if its dirty or blocked or whatever.
  • BenK's avatar
    BenK
    Explorer
    Sep 21, 2016
    Most are Hall Effect sensors and they have a permanent magnet in there...suggest
    taking a look to see if it is overloaded with iron dust most pickup from the
    street

    Brush or wipe off that dust to see if that cures the problem

    {edit}...ops...thinking of ABS sensors...most likely will not apply
    to a speedo sensor, as they normally are inside something...like the tranny, etc
  • danimal53's avatar
    danimal53
    Explorer
    Sep 21, 2016
    wnjj wrote:
    Could be that extra heat near the wheel from braking while towing is making a failing sensor worse.


    actually, when the ESC error light goes on initially, it will sometimes go off on its own. When I accelerate either passing or going uphill, the error comes back. It comes on (seemingly) more often from accelerating, not braking. My plan is to figure out which sensor is failing (if that is the issue) and just change it, see how it goes next time we take the TT out (unfortunately might not go camping again til spring :( )
  • wnjj's avatar
    wnjj
    Explorer II
    Sep 21, 2016
    Could be that extra heat near the wheel from braking while towing is making a failing sensor worse.
  • danimal53's avatar
    danimal53
    Explorer
    Sep 21, 2016
    mkirsch wrote:
    If trailer sway were causing the problem, you wouldn't be here to ask the question.

    Do you really have trailer sway? Sway gets worse with each oscillation, and requires application of trailer brakes to correct. You should NOT be tolerating this kind of sway, as sooner or later the trailer will drag or shove you into the ditch, or worse, into oncoming traffic.

    Most likely, the issue is that you have an iffy connection of broken wire in one of your ABS sensors, and the weight of the trailer compressing the suspension is causing the connection to fail intermittently.


    sway is probably the wrong word, more like "wiggle" with some heavy winds. I'm wondering if ESC is trying to correct for this, and maybe throwing off a sensor. My other thought was, as you said, the weight of the trailer messing with a sensor connection. but the weird thing is, the errors are staying on when not towing. after a couple days, all clear, no errors or anything. ill be taking a much closer look this weekend when i have some time.
  • mkirsch's avatar
    mkirsch
    Nomad II
    Sep 20, 2016
    If trailer sway were causing the problem, you wouldn't be here to ask the question.

    Do you really have trailer sway? Sway gets worse with each oscillation, and requires application of trailer brakes to correct. You should NOT be tolerating this kind of sway, as sooner or later the trailer will drag or shove you into the ditch, or worse, into oncoming traffic.

    Most likely, the issue is that you have an iffy connection of broken wire in one of your ABS sensors, and the weight of the trailer compressing the suspension is causing the connection to fail intermittently.
  • danimal53's avatar
    danimal53
    Explorer
    Sep 20, 2016
    scrubjaysnest wrote:
    We had this problem with our 2005 Grand Cherokee just going down the highway, not towing it, once the bad speed sensors were replaced no more problem. Just hope one doesn't fail when we start towing it this winter.


    yea, i've seen it's somewhat common in Jeeps, just weird that it only happens to me when towing. makes me wonder if trailer sway is causing some issue with the sensors. I might just replace them all, see if that solves it, pretty inexpensive parts
  • scrubjaysnest's avatar
    scrubjaysnest
    Explorer
    Sep 20, 2016
    We had this problem with our 2005 Grand Cherokee just going down the highway, not towing it, once the bad speed sensors were replaced no more problem. Just hope one doesn't fail when we start towing it this winter.

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