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  1. #1

    Help - Trailer brakes

    Pulling into that campground in Zion NP, I started to have brake issues.

    I know nothing about trailer brakes, but I jacked up one side to check things out.

    One tire would not turn by hand, the other spun easily. I disconnected the trailer and both tires would turn.

    I jacked up the other side. Both would not turn, unless the trailer was disconnected from the two vehicle.

    I am in need of advice, we are here for three nights, then need go to Kanab.
    95 XJ - 3.5" RE Superflex, ACOS, RC Drop Brackets, 10.5x33" BFG TA's, 4.10's, Dana 44 Rear w/Detroit, Spartan front, 4:1 T-case.
    83 Toy - 4" AllPro Fronts, Pro-Comp Rears & 1" shackle lift, 5:29's, Spool Rear, Detroit Front, Home built flatbed, Dual 2.28 cases, 35" KM2's.

  2. #2
    Is the break away triggered? There's a steel cable running to a little black box on the trailer. If the pin gets pulled out it'll go full lock. Either that or your brake controller is stuck on sending a signal. Do you have a multimeter?

  3. #3
    "Trailer disconnected" as in the electrical connection unhooked?

    I assume so-


    It takes 12V applied to the electromagnets to apply the brakes.

    First check- the brake controller- make sure it isn't cranked up to max, make sure it is still LEVELED if it's an inertia type, etc.

    2nd- Put a multimeter on the blue wire/ brake lug in the trailer plug on the vehicle side. If you have voltage there- the trailer is OK- problem is the tow vehicle side. You should only see voltage with the brake controller activated.

    3rd- Foreign voltage from another circuit (Charging circuit on the big plugs is notorious for this) will cause the brakes to apply.
    If you cross thread a bolt, there is no need for loctite.

    Run whatcha brung... And hope you brought enough.

  4. #4
    Breakaway switch functions correctly.

    Trailer disconnected for vehicle and the unlock, I no tools with me, not smart.

    I'm towing with an integrated controller (Ford).

    If it takes power to activate the brakes, the wiring or the controller would be the likely issue?

  5. #5
    tacotoy's Avatar
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    Quote Originally Posted by PovertyByJeep View Post
    "Trailer disconnected" as in the electrical connection unhooked?

    I assume so-


    It takes 12V applied to the electromagnets to apply the brakes.

    First check- the brake controller- make sure it isn't cranked up to max, make sure it is still LEVELED if it's an inertia type, etc.

    2nd- Put a multimeter on the blue wire/ brake lug in the trailer plug on the vehicle side. If you have voltage there- the trailer is OK- problem is the tow vehicle side. You should only see voltage with the brake controller activated.

    3rd- Foreign voltage from another circuit (Charging circuit on the big plugs is notorious for this) will cause the brakes to apply.
    pretty much all of this. from my days working on trailers and RV's below are my thoughts of what you need to check

    Breakaway switch first, it sounds unlikely given that it stops if you unplug the trailer, but if the 12v is dead on your trailer then this is an easy culprit as it would start getting power once you plugged the trailer into the truck

    brake control second. if it is an older voyager type controller that has to be set level, then the pendulum inside is potentially gunked up and could be locked down, normally this would present itself with jerky braking all the time, not full engagement though

    dragged trailer cable, not very likely as this would require the same dead 12v system on the trailer for the problem to only occur when you are plugged in

    a miswired vehicle or trailer plug is only a real possibility if someone has recently "fixed" something on either one, 7 pin bargman plugs ( the big plastic 1 1/4 ones) have plenty of room inside and it makes it hard to have a sudden crossfeed. if you are adapting down to an older style 6 pin berg plug, then you might have a problem there as there is 2 wiring setups for those depending on if you need reverse or not.


    Now, once you figure out what is keeping the line hot, you have some other issues, the one tire that turned when the others didnt, is either out of adjustment, or you smoked the brakes already. Since you didn't say which side you jacked up first, i am going to guess that it was the drivers side, and the front tire that would spin. On RV's that is normally where the wiring comes into the axles first and the first brake on the circuit, so this tire would see the most power and in turn the most braking effort. If this is the case you definitely need to do the shoes, and likely get the drum turned.
    hookers and blow!

  6. #6
    tacotoy's Avatar
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    Quote Originally Posted by shotgunchris View Post
    Breakaway switch functions correctly.

    Trailer disconnected for vehicle and the unlock, I no tools with me, not smart.

    I'm towing with an integrated controller (Ford).

    If it takes power to activate the brakes, the wiring or the controller would be the likely issue?
    if you pull the breakaway with the truck unplugged then the tires wont spin? if so then it is working correctly.

    Do you have a test light available? it might be worth spending a few bucks to go get one as opposed to the alternative of towing it back without brakes. What make of trailer is it?

  7. #7
    Coleman travel trailer, it's 2 years old, nothing has been done to it.

    Two vehicle is a 15 Expedition, has not been messed with.

    I had noticed jerky brakes, this was off and on.

    It locked up when I lightly tapped the brakes.

    The driver rear tire spun free.

    The safety brake works, that was one the first things I checked.

  8. #8

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    Has the camper been hooked up to the Expedition before? Any plug adapters in use, ex round 6 pin to round 7 pin?

  9. #9
    We have made around 20 trips with the trailer and Expedition.

    No adapter, straight 7 pin, both vehicles.

    I noticed when, I was messing with it yesterday, the Expedition didn't recognize the the trailer was plugged in.

    I have an appointment at the Ford dealer in St. George tomorrow.

    Wish me luck,thanks Chris.

  10. #10

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    get some spray contact cleaner and spray both the plug and receptacle - plug and unplug a few times to see if that helps.

  11. #11
    Fuses and relays associated with towing are all good?
    If it weren't for bad luck, I'd have none at all.

  12. #12
    tacotoy's Avatar
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    Quote Originally Posted by shotgunchris View Post
    We have made around 20 trips with the trailer and Expedition.

    No adapter, straight 7 pin, both vehicles.

    I noticed when, I was messing with it yesterday, the Expedition didn't recognize the the trailer was plugged in.

    I have an appointment at the Ford dealer in St. George tomorrow.

    Wish me luck,thanks Chris.
    Buy a replacement plug, sounds like something inside has melted and is not making good contact. The wires are usually color coded for where they need to go, you could do the swap with a pocket knife if you needed to.

  13. #13
    K2's Avatar
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    It's all been said, but you my find something like this at a trailer place.

    https://www.walmart.com/ip/AUDEW-12V...&wl13=&veh=sem

    Searched Google for 7 pin trailer tester.
    95 ZJ, Lift, dents, and noise.

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