Trailer Brake Problem

[IRTEXN]

Looking for some advice. I have a 16' trailer that I haul my trractor with brakes on one axle. I hooked up today and when I turn on my truck headlights, the llight on my brake controler comes on indicating the brakes are being applied. I had a friend hook up to the trailer and he gets the same indication so I know it's in the trailer. I have inspected the wiring and found one spor that was worn ( possible short) and repaired that. No help. QUESTION: If one or both of the brake magnets have gone bad, would that be the cause of this problem or what else could be my problem. I appreciate any advise you guys can offer.

Howard /forums/images/graemlins/confused.gif

 

[tawilson]

Doubtful that a bad magnet would have anything to do with it. The first thing I'd check is the ground wire. A bad ground will cause a backfeed throught the brake lights which could cause the light on your controller activate. Turn on a signal light with the headlights off and see if all your running lights flash dimly. That's another sign of a bad ground.

 

[RobS]

Definitely check the grounds, trailers are notorious for poor grounds. Also check the bulbs. Sometimes one of the dual filament bulbs (running/brake) will burn out and end up with one filament contacting the other. Can lead to some strange results /forums/images/graemlins/smile.gif

 

[MGnnr24]

I'd definitely say ground also. My boat trailer does the weirdest things, like you're describing. Found out the hard way. Testing the lights by just backing to the trailer and hooking up the wiring, bad idea, at least for me. Now I always hook trailer to ball, and latch down, this seems to make a good ground, sure made my boat trailer lights work right anyway.

 

[kennyd]

IMHO, You should never rely the ball to provide a trailer ground. You should always have a adequate ground in the wiring harness.

 

[MGnnr24]

Yes my way isn't the best way, it did work for me. Just thought I'd offer up the idea. If he was having problem with the ground that might have been a quick way to figure it out.
After that fix it however ya want.

 

[JeffRey30747]

I second kennyd's opinion on using the hitch for a ground. At night, you can easily tell a trailer using a hitch ground because the running lights will change intensity as the ground potential changes due to the movement of the hitch. It also won't work nearly as well after the ball and hitch have built up a thin layer of rust after sitting idle (until the rust wears off anyway).

Jeff

 

[songhunter]

IRTXN,
You can test for adequate grounding on the trailer two simple ways. If you have a volt-ohm-meter, set it up for a continuity test (ohmeter mode) and touch one test lead to ground on the truck and the other to ground on the trailer. A good ground should indicate 0 ohms (or such). Remember you need to have bright metal to attach ground leads. The second method is to attach a jumper cable to a bright metal ground on the trailer and the other end of the same cable to bright metal on the truck. That should provide you with a good ground between vehicle and trailer, so (if the problem is in the ground) the problem should go away. If the problem does not go away, the problem is not in the grounding. If I had to guess from what you've described, the ground lead on the trailer or connector has become corroded and no longer provides an adequate ground. You can look that over and, if that's the case, take to ground connector to the trailer off and clean all the rust and corrosion. Let us know how it comes out.

 

[Boomerbrent]

I had the same problem with my horse trailer last fall. The ground for most of the lighting was a spade bit hooked to one of the screws of the cover of the handi box used to junction wires together. I drilled a hole through the frame, soldered on a large connector and fastened to the frame using a bolt and star washer. Amazing that a $8,000 trailer, two years old would be put together so bad! But, no problems after the fix!

 

[Charlie_Iliff]

I once rewired a trailer completely, with all new lights, before finding that the problem was the ground on three different tow vehicles. The ground on the truck side often goes to a screw into the frame which gets corroded. Since that debacle, my standard first test is to run a jumper all the way from the negative pole on the truck battery to the ground lug in the trailer plug. (My trailers have redundant grounds - frame and wires to all lights, etc.)
I'd be surprised if it isn't the ground.