? on trailer brakes

[brdmkr]

If you don't have a brake module in your truck, how can you test electric brakes on a trailer?  I just bought a trailer that has brakes, but the previous owner's truck did not have a brake box, and mine does not either.  I would like to buy a box and actually use the brakes, but I can't see doing that if the brakes don't work.

He said they did work the one time he used a friend's truck to pull it.  Friend had a box. 

[sawmilllawyer]

Do you have a friend or relative that has a truck with an electric brake control box?

[brdmkr]

Likely, BUT I don't know who they might be :D

[sawguy21]

You could apply 12VDC and listen for the brakes to snap on.

[Warbird]

I would prolly jack up the trailer, take one of the wheels off, apply voltage like sawguy21 said, and make sure the brakes actuate.

[mike_van]

What Warbird said - You dont have to pull the wheel to just see if they work though, just spin it, put 12V on the blue wire [ground the frame too] It should lock right up. This link http://www.etrailer.com/faq_wiring.aspx      has lots of info on how trailers are [supposed] to be wired.

[jokers]

Electric trailers brakes need periodic manual adjustment unlike the brakes on your car or truck so don`t assume that they are not working if you can turn the wheel with voltage applied, either adjust the brakes until you are satisfied that they are working or negotiate the price of the trailer down to where you can afford to repair the brakes if they don`t work.

If they are name brand brakes you can purchase any of the individual components but it`s usually cheaper and quicker to but the backer plates with everything installed if significant replacment of components is necessary.

[Saki]

Ditto on everything said above. Generally speaking, unless they are just plumb wore out, they are a good system. There is ( at least on all the ones I have seen ) A wire ( yep mines blue too ) running to the backing plates on the hubs. There is also normally a ground wire ( bare copper or another color ) running to the backing plate or a nearby frame terminal. When the brake box sends electrical current to these brakes, a magnet energizes and sucks over against that backing plate. An arm in there which is " freewheeling" under normal operations then contacts this magnet and forces the brake shoes out to contact the hub, thereby applying the brakes. A quick down and dirty test would be to run 12 volt direct current right through the blue wire, making sure  you have a ground also. Actually better yet,  have someone else do this, and you be laying on the ground back near the hub listening for a " whine " when current is applied. This will tell you if you have functioning magnets, Check both sides this way, and then conduct the more involved tests with jacking up, spinning the tires,and checking for function. No whine, no functioning magnets, but that is not the end of the world either. These are a very simple and reliable system similar to the old drum brakes in cars. Usually if there is a problem, it can be traced to a bad wire, or more likely, a bad ground. Every year I pull a 1959 suncruiser camper trailer that has original functioning brakes I rewired about 1998. ALL of the daggone wires on that thing had rotted off of it. The camper body had corroded where it joined the camper frame to the point where it would not carry a ground. I like to NEVER found that. Was convinced I had electrical gremlins in the wiring. best of luck on your project. Steve

[sawmilllawyer]

Great link, Saki. Thanks.

[brdmkr]

Thanks for all the tips.  It sounds like it should be easy enough to test.  I may have time to check it out this weekend.  I really need to take a day or so and do some 'maintenance' (tractor, sawmill, trailers, cleaning up around the shop, etc.).  Seems strange that all this stuff comes due at about the same time.