Trailer lights not working

My trailer lights are not working. not sure if it is a fuse, relay or just needs replacement. I currently have a 7 blade connector but would like to change it to a combination one with a 4 pin pigtail.
Can anyone offer suggestions?
thanks for your help.

 

You can buy the 4 pin adapter for the 7 pin at Walmart for less than $10

Is this a new trailer? Are you sure the bulbs are good? Is the ground good? Is the trailer wired correctly for a 7 pin?

 

They sell a test plug cheap for checking the wiring from the vehicle. Pick one up and it will tell you if the problem is in the vehicle or trailer. As medic2230 says, pic up a converter plug at the same time. If the Vehicle tests good and all the lights are bad - as he says, check the ground first. Add A Temp ground to the trailer just to be sure. Grounding through the hitch is not reliable - be sure there is a good ground going through the plug to the trailer frame. Don't forget somene could have screwed up the wiring and blew all the bulbs. Be sure to checks those as well. Start checking ONE signal line at a time - such as a directional signal. Turn on the signal, Check the plug from your truck, then trace to the light bulb and it's ground.

 

The utility trailer is not new and the bulbs are good. The lights on my popup camper also do not work when I connected to it but did work when my friend towed it.

 

Get the test plug - check the truck first. https://www.etrailer.com/question-31721.html

 

I'll get someone to help me check the ground issue. It had worked previously, (months ago...) It is the connector that came with the truck.

 

https://www.etrailer.com/Accessories-and-Parts/Tow-Ready/TR20117.html

 

I am having a similar problem. I have a 2013 taco with a factory tow package, (I believe)(bought the truck new with the hitch/etc on it) and it has 4 pin connector. None of the trailer lights work. They worked in 2022 for sure. Tail lights/trun/brake all work normally on the truck itself. I also have a tester, (Hopkins Endurance Easy-pull LED Test 4 Flat Trailer Side (12") in the Trailer Parts & Accessories department at Lowes.com) and none of the tester leds illuminate. Same problem with 2 different (boat) trailers. - no lights work. So, the problem appears to be in the truck. Tracing the wiring from the on-truck trailer (4 pin) connector I see the harness goes up into the left (drivers side) tail-light. Looking there I see a white ground wire that is connected to a stud on the truck bed sheetmetal. I removed the wire terminator eyelet from the stud, cleaned the stud and eyelet with a wire brush, applied some dielectric grease and re-installed the eyelet/wire on the stud. Still no money... Connected a jumper from battery negative terminal to the stud mentioned above (just in case there was a body (bed) grounding problem. Nothing.

There is a black junction box right there in the trailer wiring behind the left tail light. It is about 1.25" thick, x 2" x 2". What is that?

Any other thoughts?

 

Here is a pic of the “black box” (near the center of the pic). Note the white ground wire in the upper part of the pic.

 

That's not the factory tow package, trucks with the factory tow package will have a 7 way plug and not converter box.
If all the lights work properly on the truck odds are the power/ground (if it has external power/ground) to the converter box is bad or the box itself is bad.

 

Thanks Dm93. Maybe the tow package is dealer installed. Like I said, it was on the truck when I bought it new, but again, maybe the dealer put it on. I will say that whoever did it did a nice job of putting the new wiring in wire loom, etc.

My plan for tomorrow is:
1) check for fuses under the hood, etc. - but I don't think that is it.
2) check the ground again. Maybe run another ground wire.
3) I don't think the converter box has a separate power wire but I'll make sure.
4) Consider getting a replacement converter box. I'd prefer plug and play - would rather not be chopping into my factory wiring... I see E-trailer has some offerings: 2013 Toyota Tacoma Trailer Wiring 4 Flat | etrailer.com

BTW:
This all started when I bought another boat (with trailer) that was apparently wired by a technically challenged individual on the cheap... Maybe that trailer mis-wiring messed up the converter box. I rewired it completely and installed LED lights. Then sold the boat/trailer combo.

Thanks much for your help!

 

It's definitely not a factory tow package, like I said trucks with the factory towing package have a 7 way plug with dedicated trailer wiring (no converter box) in addition to an engine oil cooler, larger alternator & battery, transmission cooler (A/T), and class IV hitch.
I'm not sure if trucks without the tow package still come with a 4 way plug or if that is a dealer add on but I think it's a dealer add on.

 

You are correct - I just looked at the window sticker - that I had in my file - and found that it did NOT list the tow package so it IS a dealer add on.

Lesson learned: get the factory tow package - BTW: I'm hoping to get a 2024 taco.

I'll update you all once I figure the prob out.

 

I installed the same on my '13, and it has held up fine so far.

There are of course and input and output sides to the converter box. Use a DVM on the input circuit and run through all your lighting combos. If those are all hot, the box is probably bad. You can test the box outputs too of course. If they are good, you have a problem in the bit of harness from the box to the plug.

My bet is the box has failed.

 

I got the Kurt converter box/t-connect plug & play kit and it fixed the problem. Thanks much to DM93, clearwater and all for your help and mini education. This is a great place!!

 

When you want to tag someone do it so...

@red worktruck