Trailer light question

[K. Lane]

I hook up my stock trailer and do the “let’s check the lights routine”
right blinker- check
Left blinker- check
Emerg. Flasher- check
Brake lights- check
Turn on the head lights and all the marker lights work but I have no tail lights


All fuses are good
All lights on tow vehicle are working
No burnt filaments on trailer light bulbs
All wiring and connection points seem fine


What gives??

[M16]

Usually the ground is bad or broken wire.

[Old Goat1]

Bad ground on the trailer. Save yourself some steps. Check right blinker, left blinker, they are the same wire as brake lights and emergency flashers. Check running lights with blinkers. If it's a bad trailer ground it will blink dim on the trailer.

[friscopaint]

I hate trailer lights !

[bboswell]

Bad ground on the trailer. Save yourself some steps. Check right blinker, left blinker, they are the same wire as brake lights and emergency flashers. Check running lights with blinkers. If it's a bad trailer ground it will blink dim on the trailer.

This

[brushtrooper]

If all else fails, make sure the ball is clean from rust/paint same for inside of trailer coupler. Or hook it up and to some hard right/hard left turns back and forth, it will eventually ground through the ball

[Rick]

Blinkers and brakes work off the same filament. Running lights of other filament. depends on how the wire is run on the trailer, but I am betting it is break in the brown wire somewhere past the running lights. Could be bulbs, but not likely they would go out at same time

[Mike D]

Trailer light question

Usually the ground is bad or broken wire.

Yep Bad ground.


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[Pedernal]

If your trailer marker lights are working but not your tail lights it could be a cut wire (usually brown) going to the tail lights. Do you have a multi meter?? If so check continuity to ground at the bulb housing to trailer frame. if your blinkers are working you should have good ground. If your ground is good, check for voltage at the bulb housing for the tail light terminal.

[lost cajun]

I would check the fuses again, both under dash and under hood. Had the same thing happen.


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[critter69]

It’s best to wire a ground, from your truck to the trailer, via your plug.then the rust and poor lighting ( dim lights) should not be an issue.

[cva34]

Trailer ground

It’s best to wire a ground, from your truck to the trailer, via your plug.then the rust and poor lighting ( dim lights) should not be an issue.

So true...That going thru Ball is iffy and unstable...There are multiple culprits ball surface /hitch surface /bumper bolts to frame/ball hitch bolts to trailer tongue..

[Arrowslinger1]

Never heard of some lights working and some not with a bad ground. Usually no lights work with a bad ground. I had a bad fuse tonight with no running lights. Blinkers and brake lights worked fine. Changed out the fuse and running lights came back. There’s about 4-5 different fuses for all the trailer towing fuse positions. At least there is on Ram 2500 newer models.

[Pedernal]

Never heard of some lights working and some not with a bad ground. Usually no lights work with a bad ground. I had a bad fuse tonight with no running lights. Blinkers and brake lights worked fine. Changed out the fuse and running lights came back. There’s about 4-5 different fuses for all the trailer towing fuse positions. At least there is on Ram 2500 newer models.

This has been my experiance as well. Not sure if it's on all brands but newer model Rams have a separate fuse for trailer brake lights and trailer running lights and are totally different circuits from the actuall truck lights.

[CabezaBlanca]

It takes two things to make a trailer light work, 12 VDC+ and 12 VDC-. You don't have one or the other.