Trailer running lights...No Work

Anyone have issue with trailer lights? Turn signals and brake lights are good. No tail lights. Checking the truck wiring voltage show no voltage between ground terminal and tail light (brown wire) position in the 4-prong flat connector (lights are turned on). Ideas? BTW all lights are good when trailer is connected to other vehicles.

 

Did you figure this out? I’m having the same issue. Plugged in a different set of lights and a different trailer, and no go. It’s definitely the truck. 2016 TRD OFF ROAD.

 

Check the fuses and follow the wires look for breaks or pinches. Check your grounds.

 

Most likely a bad ground between trailer and truck. To test, use a length of wire connected to a clean spot on each frame. I still have a length of wire with a clamp on each end, used for U-haul trailers years ago.

 

Since you’re checking at 4 way flat connector I’m assuming you have a 7 round adapter plugged in? Maybe the newer Tacoma’s come with a factory 4-way along with the 7 round? If you are using an adapter I’d suggest removing it and checking voltage at the pin on the main 7 pin connector. It doesn’t take much for those things to act up and not work correctly. Your tail lights working fine on the truck?

 

I had similar symptoms this past summer. Check a fuse in the under hood panel; you’ll find it on the driver’s side. It’s the green 30 amp blade fuse next to the pink square-ish one. The fuse panel lid will have a puller and replacement 30 amp fuse.

 

Thanks guys! I’ll check it out tomorrow and let you know. Sounds like I’ll start with the green 30amp. Then work on checking the grounds.

1) yes it’s a 7 pin and 4 pin model. My trailer is a 4 pin. I checked the trailer with a 7 pin to 4 pin converter and it’s the same. No running lights from either of the sockets. 2016 model.

2) @Killowatt , so when I look to check for grounds, I should use a length of wire and connect what to what?

3) can I just use my multimeter to check the voltage? The running light pin should always be on, and the brakes and flashers only when activated, correct? I assume I just put the hot (red) lead in the pin, and the black will go to ground (frame).

Thanks again guys. This forum is awesome.

 

Just find a clean spot on the frame of the trailer and the truck, under a bolt maybe, or use alligator clips to hold in place at each end.

 

It was the green fuse. Thanks guys.

 

Dude you just saved me a headache. I love that these threads can help folks out years later. Mine issue was a bad fuse.

 

I just built a small harbor freight trailer and while installing and testing the lights after assembling this 1000 PC jigsaw puzzle, realized my running lights didn't work (trailer only).... a quick Google search led me here (as usual, not my first time) and I finally joined just to say "Thank You!" for this thread.... it was a 2 minute fix and it was even the first fuse I checked. Thanks again!

 

Thanks for the info!!

 

30 amp mini fuse blown. Next to large 30amp 2017 TRD Offroad 4x4

 

Thank you. Same thing. Fuse blown. LoL did check here first so yeah I checked ground and for breaks in the wire. Stopped to eat and thought I would double check the forum. Checked the fuse and sure enough bad fuse. Any idea what pops it. Or is everyone just carrying extras? My trailer has no issues with my other rigs so I'm thinking is something else. All the lights are led (utility trailer).

Thanks again.
Brian.

 

because there was a problem. that's the entire reason fuses exist.

i would verify that something isn't wrong on the trailer.

 

Correct ….last time I had this issue, the tow ball was badly rusted

 

My 2019 uses the 7-connector but the trailer lights only light up when the headlight selector is set to one of the last two notches only, if I leave it on the DRL setting like I usually drive then there is no trailer lights when towing.

 

You won't have running lights with DRL selected, but you should still have brake lights and turn signals on the trailer.