Trailer brake problem...

[Baucom]

My 16' Hurst 7K trailer has a single brake axle. My problem is that when I plug in the lights and start to moving, as soon as the trailer moves the left wheel brake locks. The right wheel brake functions as it should. When I unplug the trailer from the truck, the left wheel brake unlocks. My first thought was the breakaway switch, but it's fine. I've pulled the drum off and looked at the brakes, and nothing appears to be obviously wrong. I've been lucky and never had any problems with electric brakes before, so I need some guidance on this one. Any suggestions? Thanks in advance.

 

[Egon]

Check the wiring with a meter.

 

[Diamondpilot]

Even if it were the brake away it would lock both brakes since they are wired together, not independently.

If you have torn down both assemblies and they appear fine, clean of grease, and in adjustment there are only a few possibilities. One is a bent spindle but I do not think this is likely due to you just looking things over. The more probable explanation is there is a problem with the wiring and the brake that is locking up is wired directly to the brake light circuit on the trailer giving it full 12Volts and that = lock up. It could also be just a short or it could be a total screw up in the wiring.

Like Egon said get out the meter.

Chris

 

[schmism]

as soon as the trailer moves the left wheel brake locks. The right wheel brake functions as it should.

Id jack the trailer up and verify what the wheels are doing. How do you know the right wheel is brakeing when you press on the brake?

if i had to guess the brakes are wired wrong (or your 7 way hookup is) and the right wheel isnt brakeing at all. (ie e-magnet is toast)

 

[simonmeridew]

It sounds like there may be 12v power back feeding to the brake wire that supplies the wheel that has the brake problem. For example, if the ground is bad on one of the lights, the power will search for a ground and find one; if there is some wire cross connected, either intentionally or inadvertently to the brake circuit, it will activate the brake. This can be very mysterious, and cause of much blue air not suitable for children. Meanwhile the brake that appparently isn't activating, may just be so far out of adjustment(or the magnet bad) that you can't tell but it may be trying to work.
simonmeridew

 

[om21braz]

Not much fun figuring out wiring problems, especially by yourself. Check all simple stuff first, wiring at plug, no loose wires anywhere, etc. Good Luck!

 

[Mace Canute]

Also, don't forget to check your grounds. Many an electrical problem has been the result of bad grounds.

 

[Baucom]

I know the RH wheel brakes when I step on the brake pedal because the rh tire locks and slides when I pull forward and step on the brake (unloaded trailer in the grass), as soon as I let off the brake the RH wheel unlocks and begins rolling again. The brakes worked fine the last time I used the trailer...this time I hooked to it and it was like the LH brake was hung.

Id jack the trailer up and verify what the wheels are doing. How do you know the right wheel is brakeing when you press on the brake?

I bought this trailer new, and all of the lights have always worked and the brakes worked fine--until now. All of the lights still work...

There are some good ideas here that I hadn't thought of that I'll have to investigate. Thanks, and keep the ideas coming...

 

[tommu56]

Check the current (not the voltage)on wires to that brakes individually and by that I mean both wires on each brake assy.

Maybe it is a mechanical problem like magnet stuck to drum or some foreign object jamming brake band.

If you didn't know the magnet grabs the face of the drum and and the wheel movement (moving the magnet stuck to it) moves the brake band against the inside bore of the brake drum.

tom

 

[Soundguy]

I had a similar problem with a big tex car hauler with a factory 6 pin plug. i bought a 6 to 7 pin plug so I could tow it with my yukon or f250 and the brakes locked on it.. turns out there are a 'couple' wire 'standards'.. I had to swap a wire in the 6to7 adapter and then it worked fine.. apparrently power and brake power were swapped..

that or as the others said.. a short from power to brake.. however as DP said.. the brakes should be wired parallel.. so if one is getting power... the other should be as well.

I'd jack them up and spin them by hand while a couple helpers plugged in the receps and hit brakes for you.. etc. that and a vom as egon said will help.. heck.. even a test lamp..

post back

what tow vehicle?

factory trailer plug?

6 or 7 pin.. or?

soundguy

 

[Baucom]

2007 Nissan Titan tow vehicle with a 6 pin trailer plug and 7 pin on the truck. Using a Hoppy 6-7 pin adapter. Nothing has changed in my towing setup in the past 2 years and it has always worked until the LH brake hung this time. The heat index here has been too HOT to pull the trailer in the driveway and work on it...hopefully in a couple of days it'll be back down in the low 90's and I can test a few theories.

It would seem to me that since the setup I have has always worked in the past, and since the RH brake is functioning properly, that whatever is wrong must be either something mechanical inside the brake drum or in the wiring that runs into the LH brake assembly.

My gut says the problem is electrical, because the LH brake only hangs when the lights are plugged in. I can pull the trailer all day without the wiring plugged into the truck with no problems, but when I plug in the trailer wiring to the truck, I pull up 2 feet and the left wheel is sliding. If the problem were mechanical, such as the magnet stuck to the drum or a foreign object jamming the brake band, then it should happen all the time, not just when the lights are hooked up, right?

 

[Soundguy]

only fly in the ointment is those brakes are paralleled. have to be. there is only 1 sypply line on the plug for both magnets.. that means the 1 wire int he trailer plug runs to both magnets.. thus if power was shorted over to a wire near the left axle.. the right axle would see it too.

if it was electrical.. it would make me think the brake not locking up was simply not working..

soundguy

 

[Soundguy]

ps.. didn't repalce that 6 to 7 pin adapter did ya?

soundguy

 

[Baucom]

No, it's the same adapter I've been using for the past couple of years.

ps.. didn't repalce that 6 to 7 pin adapter did ya?

soundguy

 

[Skyco]

Good point on the 6 to 7 pin adapter..I found out years ago there are two "standards" for 6 pin wiring and the wrong one will cause brake problems.
Went down the street with someone elses trailer and had brake problems.
It had the other "standard" for 6 pin wiring.
Some 6 pin adapters point this out and have a quick change provision to swap two wires.
http://www.hopkinstowingsolutions.com/doc/trailer_wiring_codes.pdf

 

[Diamondpilot]

Like SG said the way they are wired is one wire runs from the tongue down one side of the trailer to the first brake. It then runs across the axle to the second brake. I think this is where you will find the issue from what you have told us. My guess is a wire is chaffed. Sometimes they run though the axle so be careful pulling a new wire through.

Chris

 

[forester2]

Don't know if this will help, but I had a problem with both brakes locking up that drove me crazy. Finally traced it to the plug on the trailer side. One stray strand from the brake wire was touching on an adjacent light terminal. My plug was the style where the outer covering was removable to run wires into screw terminals.

 

[Soundguy]

yep.. my hopkins adapter was a quick change.. just remove a screw slide apart, swap 2 wires and go..

soundguy

Good point on the 6 to 7 pin adapter..I found out years ago there are two "standards" for 6 pin wiring and the wrong one will cause brake problems.
Went down the street with someone elses trailer and had brake problems.
It had the other "standard" for 6 pin wiring.
Some 6 pin adapters point this out and have a quick change provision to swap two wires.
http://www.hopkinstowingsolutions.com/doc/trailer_wiring_codes.pdf

 

[Soundguy]

my dexter axles on my 16' were that way.. no grommets.. just single insulated wires run thru.. and chaffed. I ran dual insulated wires, and pushed some 1/4" fuel line onto the holes as grommets. been fine since. also had some chincey tap fold over splices from the dealer.. replaced those too with sealed connectors

soundguy

Like SG said the way they are wired is one wire runs from the tongue down one side of the trailer to the first brake. It then runs across the axle to the second brake. I think this is where you will find the issue from what you have told us. My guess is a wire is chaffed. Sometimes they run though the axle so be careful pulling a new wire through.

Chris

 

[Iplayfarmer]

I have one fix for trailer wiring problems... I rewire the whole thing. I've never spent less time chasing a gremlin than I would have spent just running new wire. I buy any extension cord I can find at garage sales, auctions, etc. so the cost of the wire is negligable.