Trailer wiring question

4x4v8 · 12-21-2011, 12:53 PM

So I have a problem with my 6x12 enclosed trailer. Some of the lights aren't working after I fried a wire and I have no idea how to troubleshoot for problems. Basically, the wire to my side markers, over my fenders, touched the tires and it sparked a fire on the wire. Since then some lights don't work. I tried cutting out the portion of the wire that burned and replaced the side marker but the same lights still don't work.

brake lights- ok
signals- ok
interior light- not working
running lights/side markers- not working

Does anyone know what some possible reasons may be for this? Or any good sources online that I can look at for more info?

Thanks!

Kung · 12-21-2011, 06:59 PM

Well, unfortunately, you might have shorted out something internally. What I don't understand - and this is the reason you might have shorted something - is because the trailer lights come off the same circuit as the brake lights & signals, and they're not fused. (In other words, a straight shot from the front to the back).

Easiest thing to do would be to see if any fuses are blown up front. If everything is good, then I would either

a) get one of those $5 4-pin (I assume that's what you have on your 4Runner) testers and plug it in, and see what you have, OR

b) if you have a Fluke (ammeter/voltmeter/ohmmeter), test and see what the readings are on all 4 pins. I would *assume* you'll see 12 VDC.

If either method reveals something, I'm betting, at the least, you've either blown a fuse (or fuses) or the tail light converter, or both.

maine runner · 02-21-2012, 10:04 AM

In addition to the above, follow the ground wires.

A large percentage of trailer lighting problems are traced to a bad ground wire.

On a typical utility or boat trailer, each light has either a ground wire or the stud is the ground. If your marker light has a wire, remove the wire, clean the exposed strands as well as where it attaches to the frame. It needs to contact bare metal.

When rewiring, running dedicated ground wires to a central bolt is one way to eliminate short circuits.

Kung · 02-21-2012, 05:43 PM

Quote:

Originally Posted by maine runner

In addition to the above, follow the ground wires.

A large percentage of trailer lighting problems are traced to a bad ground wire.

On a typical utility or boat trailer, each light has either a ground wire or the stud is the ground. If your marker light has a wire, remove the wire, clean the exposed strands as well as where it attaches to the frame. It needs to contact bare metal.

When rewiring, running dedicated ground wires to a central bolt is one way to eliminate short circuits.

Good post. As a matter of fact, while I went ahead and removed the entire Toyota tail light converter system, I believe that the entire problem with it stemmed from just that - a faulty ground connection. (Though it wasn't a problem with the ground connection itself - the wire just flat fell apart.)

What I did to attach to ground was to undo one of the bolts holding the tie-down D-rings. I then hit the metal below it up with some sandpaper to expose metal, and then stuck the ground connection between the body and the D-ring bolt. It's worked fantastically.