Lighting Problem - Diesel Forum

damien · 08-16-2007, 01:42 PM

I installed a new lighting kit on my 8' utility trailer, and I went to do the final light check, only to find that when I apply the brakes, my vehicle brake lights work, and my trailer's doesn't. Ground is good (on trailer and vehicle), running and turn lights are good. HELP! Thanks all.

STurbo90 · 08-16-2007, 02:23 PM

something is not right,

the turn signals are the same wires as the brake on a two filament bulb, the low side is marker lamps, the high is turn/stop,

so if the turns signals work,

it sure sounds like the ground is bad,

if the ground is bad, when you signal, only one side gets power, the other side rests at ground and will complete the circuit, when you brake both wires get power, eliminating the ground path, so........?

do the hazards work?

damien · 08-21-2007, 02:47 PM

Hazards DO work, I'm thinking a weak flasher(s).

Bassman349 · 08-21-2007, 04:21 PM

I wouldn't think that the flasher would have anything to do with your trailer brake lights not working.

If left and right turn signals and 4-ways are all working on the trailer, there's just no good reason why the brake lights on the trailer don't light up. As another poster mentioned, the brake lights use the same filament and same feed as the turn signals.

Dualie · 08-21-2007, 11:27 PM

I'm thinking it definitely has to do with your truck. If the signals work then the stop lamps should work. I would try the trailer on a different truck then go from there.

STurbo90 · 08-22-2007, 01:15 AM

[ QUOTE ]
Hazards DO work, I'm thinking a weak flasher(s).

[/ QUOTE ]

flasher does not operate the brake lights,

maybe I misunderstood your first post,

the Trucks:

brake, turn signals, running lights work?

but the Trailers:

Brake lights do not work,

BUT the turn signals and running lights work?????

including the hazards???

if so, the flasher is working????

Dualie · 08-22-2007, 02:57 AM

IF the turn signals work on the trailer then the problem is not in the trailer. I would check the trailer stop lamp fuse in the truck.

TrailerHauler · 08-24-2007, 01:31 AM

Sounds like ground to me.
I own a trailer dealer, and the trailers don't come with plugs from the factory we have to put them on. The only problem we've ever had has been ground. when the running lights are on and the brake lights come on, on the truck, they go off on the trailer.

If your sure it's not ground like someone else said, try it on someone else's truck

STurbo90 · 08-24-2007, 04:16 AM

[ QUOTE ]
IF the turn signals work on the trailer then the problem is not in the trailer. I would check the trailer stop lamp fuse in the truck.

[/ QUOTE ]

There is not a dedicated stop lamp fuse for the trailer harness, only a brake fuse for the truck,

the trailer harness does have dedicated turn left/right fuses, but they must be good since he says the trailer signals work,

he hasn't been back so he must have figured it out?