Trailer= I'm stumped

[Jmnhunter]

alright, it started like this: original lights-drivers side worked at all elements, passenger side not at all. bought a new kit and its a standard wiring kit from blazer for a 17ft trailer total length, turned on the headlights, and both drivers side and passenger side works -good so far. tested out the 4-ways only drivers side worked, same with the brake lights -passenger side did not work at all..

so what i did so far to figure out the passenger side:

-new connections towards the passenger side lights (3) =nothing different

-kept the headlights on with the flashers going and it worked but it was a weaker flicker from the passenger side than the drivers side.

-put a 4 way tester for just the truck connections and everything worked

-tested the old drivers side assemblely with the passenger side wires and the same thing happened-running lights worked but no brake or four ways. (it worked fine when it was on the drivers side)

what do you think? bad trailerlight assembly?

[Whoaru99]

Any time I have to check trailer light trouble I double, triple, and quadruple check the ground(s) on the trailer and on the vehicle.

Weird stuff happens when there isn't a good, solid ground.

[Esox_Magnum]

Simplest easiest way to fix a trailer light problem is to replace everything new.

[FMSmitty]

Narrow it down to the trailer for sure by hooking up to a known working truck or hook your truck up to another trailer. Once isolated to just the trailer, its either the main connector, bulbs, ground or splice connections. You didn't mention whether you spliced into the harness for side marker lights? If you did, and used the blue cheapo connectors that come with the kit, that is probably the issue. Also make sure the trailer coupler is fitting the ball TIGHT. They have an adjustment nut and it makes a big difference in the ground.

[Smoker]

I never trust the coupler as a groung. I would run a wire to the frame and make sure there is no paint or rust under the bolt. If it is a alum. trailer then you will need to run a gound wire to all the lights. It could be the grounding spot for that one light because you said you tryed the good light there also and it did the same thing.

[delmuts]

I agree . Check and recheck the ground!

[Pat K]

I'll only spend an hour trying to track down trailer wiring problems. Then I tear out all the old and replace it with new. Saves time and is less frustrating.

99% of the time it is a lose or corroded ground.

[Jmnhunter]

sorry didnt make it clear, it is a new kit.

I also learned i could not use the cheap splicers that came with the kit and had to use actual butt spices.

i'll recheck the ground and try a different vehicle hooked up to it to see if its my truck or the kit.

there is a ground wire going to the frame of the trailer and a seperate one going to the frame of my hitch.

thanks for the tips; i'll let you know

[Bigtom]

I have bought light kits that are cheep by having small wires and a bad 4 way plug. They go right in the garbage. That saying, I would double check your wires at the 4 way that are in the molded plastic plug.

Did you check the back side of the light bulb for a good connection with a test light?

Some trailer lights that have 2 bolts on the back are likely to have a bad gound in the bolt holes. I swiched to new led lights that have a gound wire not bolt and they work great.

Good luck.

[Pat K]

A quick way to check your ground is to hook a jumper cable to a clean spot on the truck frame and the other end to a clean spot on the trailer.

[Jmnhunter]

went out to the garage; re connected the side marker wire to the main ground wire of the passenger side, reconnected the ground wire onto a new spot on the trailer; still same issue, everything but the brake/blinker on the passenger side; also tried wd-40 for a better connection of the bulb; nothing, looked at the 2 connections and they were good.

circuit tester on the truck's wire connector is working fine. must be a bad assembly?

[sx2]

it could be a bad bulb on the passenger side. Your low sided is your running lights and your high side is your blinker and brake. There is two filaments in the bulb. That's if you have the bulb type lights.

[gunmunky]

When I have trailer light issues I start by using my (winter) flasher battery as a power source. I hook up the ground(neg) to the trailer frame and then use a wire with both ends striped and go from the positive terminal to each connector on the trailer plug. This way I am sure to have a good ground and I can verify the trailer lights are bright enough. If all this is good and then I hook it up to the tow vehicle and check it all over again. I to never trust the coupler as ground and always hook the ground wire thru the plug. Good luck.

[BoxMN]

Run a temp wire from the ground on the working light to the gorund on the non-working light. If it then works, it is the ground on that non-working light. That is my guess

[Jmnhunter]

**tried a different bulb too, but nothing. I will try the ground wire trick too

[Jeremy airjer W]

I'd have to agree with it sounding like a bad ground on the passenger side. I had couple trailers last year that I ended up running ground wires from the four way connector all the way back to the light assemblies to solve similar issues. The problem was the trailers where bolted together and over time the bolts and holes rusted leaving a poor path to ground. The simplest solution was to run the individual ground wires and no longer rely on the trailer frame for a ground.

[Jmnhunter]

as of right now the ground from the passenger side is relying on the metal plate that it bolts on; i will try to add another ground wire from the back of the light assembly to a cleaner spot on the frame?

[Jeremy airjer W]

You'll probably be better off running that wire all the way to the tongue of the trailer where the white wire form the four is is connected.

[Jmnhunter]

well tried her again today, tightened the mounting bolts of the light, nothing, then while i had the 4-way flashers going i started to tap the bottom of the light then it flickered, then stayed; now its working. Must be a loose connection in the assembly?

i kept retrying it and its been coming on, i did shake the back of the trailer and noticed a weak flicker of the light.. but i think it is good to go...

[hanson]

Quickest way to solve trailer light problems is to actually run ground wires back to all your lights as a few others have mentioned. Relying on the trailer frame to carry the ground is just a joke IMO. Solder and heat shrink all the connections and you shouldn't have too many light problems in the future.

[Jmnhunter]

alright, so as you guys mention just connecting 2 wires (one from the passenger and driver) all the way to the white wire from the connector to the assemblies, where on the light assemblies would i need to connect it to?

[BoxMN]

To the ground - the white. But really if one of yourt rear lights is working well, then all you need is to connect the ground (add a white wire between them) from the working light to the non-working. Shorter run = less wire needed, and accomplishes the same result. If they both don't work, then just run a white (ok, you can use any color wire, but might as well keep it consistent) from the white up by the connecter to one of those rear lights, since they will already be connected - thus connecting the ground. Hope that made sense... And like I said earlier, you can test it out first without totally zip tying and soldering or connecting finally, just by using a piece of wire from one light the other, testing for bad ground. If the "bad" light then works, then you know it is a ground problem at that light. Probably rusty connection point... Good luck!

[Jmnhunter]

hey box, i have 2 wires from the assembly brown one (running lights i believe) and a green for my turn/brake light, so after running the white wire from the 4 way connector what do i connect it to the assembly?

thanks

[PierBridge]

Sounds like he has no ground wire on the lights as can be the case.

[Smoker]

On some lights the mounting stud is the ground so you will need to put the white wire to the mounting stud.

[BoxMN]

On some lights the mounting stud is the ground so you will need to put the white wire to the mounting stud.

Yep, what he said since you are running a new ground to one of the lights, just run another white line to the other light stud. You might have to take the light off to see what stud it needs to connect to. There would be a wire or brass looking bent metal piece or maybe just a piece of steel around the stud... sounds like a b-rated Hollywood movie