Trailer tailight question

[Woodywoodchuck]

Hi, I have a small trailer thats only 8 feet long. The right tailight and blinker doesnt work. I checked for continuity with a tester 6 inches before light and its good. I also checked for any exposed wires and taped them up in case it was grounding out. The ground, out of plug that I attach to a small bolt on trailer must be working incorrectly cause I cant get it tight but no doubt the ground is touching the metal of trailer just not super tight.
I changed the bulbs, I know its not a fuse cause the left side works.
Any suggestions what else could be wrong? I can replace the wire to that side? I do have a voltage tester but never have used it nor I have I opened it.

So ground? The wires coming in to taillight are 6 inches long, where its soddered to back of each bulb insert. I cant see them but the chance of both bulbs sodders off are slim.

Thanks

[westcoastplumber]

Re: Trailer tailight question

I had the sam problem with a trailer I built and had to wire, all ne wires and no tailight on one side, I had to sand the area of the ground and get it tight to the steel.

I also had my harness hooked up wron, which I fixed, then found out the ground was bad.

Amazing how important a ground is.

[threecreeks3]

Re: Trailer tailight question

i've messed with a lot of trailers rv's etc ..99% of the time its a bad ground..its only 12 volts an needs all the good help it can get to work right.A suggestion..fix the problem then fill everything with silicone grease...look at napa etc for that its cheap..silicone dielectric grease is what it is..keeps corrosion out a lot..old truckers used regular old grease in light bulbs trailer connectors etc..that stuffs a mess and a real headache to clean up after it hardens..the silicone won't harden.loosen up the lights clean where they bolt up a dab of grease tighten back up ..etc .My trailers and vehicles get every bulb and trailer connections coated well with it
Sam

[Wild Weasel]

Re: Trailer tailight question

Your volt meter will figure this one out. I always test my grounds using the voltmeter when doing automotive wiring. You'd be surprised at the sorts of connections you figure will be foolproof but aren't. Even a rusty bolt can kill your connection.

Use the voltmeter and test to ensure you've got 12-13 volts or so from your power wire to your ground. If not, try another ground to ensure the power is there.

[wbrooks]

Re: Trailer tailight question

Judging by your location it is likely a corrosion problem.
Getting that ground bolt tight is a good idea but not the problem as the left side works. Break out that voltmeter or a 12V tester with a bulb would be better.
Since your running lights are a single wire and they work on the left side you have a ground problem on your right tail light.
Use the volt meter to test continuity between the bulb socket case (part that holds the bulb not the two 12V nibs at the bottom) and the frame of the trailer. Look for where the right tail light gets the ground and test that wire or check where the light is bolted to the trailer frame

[Woodywoodchuck]

Re: Trailer tailight question

Thanks I will report back on this.

[ump107]

Re: Trailer tailight question

A lot of the Trailer connections I have seen the ground just goes to the frame of the trailer. If you have a good ground coming off of the vehicle and through the connector, tap off the ground where it contacts the frame and run separate grounds to your taillights (sometimes it's a pain). Most of the time this works well. I had a 30 year old utility trailer that I did this to due to it being overly rusty, the lights continued to work until the floor failed and I junked the trailer.

[dufferjames]

Re: Trailer tailight question

I have a 22' trailer and the each tail/brake light fixture has a ground connection to the frame. With your tail lights on, and bulbs in place, measure with your voltmeter (DC volts) at the ground connection (the wire from taillight that attaches to frame). You should measure zero (0) volts. If there is voltage, then the ground connection is no good or very poor. Since one side is working, it appears that the trailer frame is indeed grounded, so it is only the side fixture that may have the ground trouble. Good luck. I prefer to use the voltage meter, as an ohmmeter can easily be damaged if measuring resistance and voltage is present!!