So i have a 2011 ford ranger xlt, Came with a factory tow package and has a 4 pin connector for the trailer lights. The brake lights and turn signals work but i cant seem to get the running lights working. Ive checked the #2 and #31 fuses in the fuse bow inside the cab and they both seem to be fine. Any ideas on how i can fix this? Its for a led tail light strip

 

I assume Park lights work on the truck, so the Park light relay is working

Have you tested connector for 12volts with park lights on, it will be a brown or grey wire
Brake/turn use same wire, one for left side and 1 for right side

Did you check fuse #2 for 12v with park lights on?

Worst case is that you can tap a grey wire at the rear and install an inline fuse, 5amp, to get trailer park lights back, but better to find the issue

 

So i did some tinkering today to try and solve the issue. The brown wire reads 11.99volts so its fine. I cut the trailer 4 pin off and was just hard wiring it to see if it was bad plug. If i have just brown plugged in running lights works fine. Any time i put the turns/brake cables in it kills the running lights and only the turns / brake lights work. I have also tried running a separate ground so its not coming from the harness. And same issue arises. So then i spliced a wire into the license plate light to try getting the running light power from that. And it works until i hook up the other 2 wires for turn and brake. At a lost of words why they work separately but not together. Its for one of those led strips that go underneath the tailgate and i tried it with another truck, and no issues

 

so in short. If i have just the brown wired to the plug and ground i get my running lights. But.... When i plug in the rest of the wires. Left/Right turn/brake, the running lights do not work but everything else does. And that's even with me trying to pull running light power from taillight or the license plate light. I haven't tried seeing what the voltage is on the #2 fuse though. Because i feel like if the running lights are working when i have just them wired then it shouldn't have anything to do with the fuse right?

 

That is an odd symptom, there is no electrical connection between running light wire and the turn/brake wires, totally separate systems, on purpose

So your truck lights act the same?
so not a "trailer" wiring specific issue?

If its trailer specific then problem is in wiring on the trailer, not the truck

Test brown wire unplugged from trailer and with turn signal and running lights on, to see if brown wire loses voltage

And 11.9 volts is NOT OK
Unless your battery is bad
Test battery voltage, key off, 12.3 to 12.8volts is what you should see, 12.2v or under is a failing battery, not your problem for this but a problem in general

If battery is........say 12.5v then thats what you should see on the brown wire with running lights on, well maybe 12.4v with lights on
If iis lower then you have a corroded connection somewhere on that brown wire to the back of vehicle

If you are using the Ground wire on the trailer plug, as the ground to test voltage, try using frame as ground, if voltage goes up then the trailer connectors ground is corroded which could cause the problem

 

My taillights have no issues at all. They all stay working and nothing is wrong with them. The only issue is for the led Tail bar. I rechecked the voltage on the brown wire, and got 12.5 volts. However the right/left blinker wires were only getting 12 volts. I have not tried checking the voltage with the blinker running on the brown wire yet. And like i said previously the running lights on the Led Bar will only work if i have just the brown and ground plugged in. Any time is gets any connection from the blinker wires the running lights shut off. But the brake lights and turn signals work fine. And that's why i thought the brown wire was bad. But i even tried getting the power from a different part of the harness. They all are connected together somehow right? If thats the case then technically i feel like my normal tail lights should be having problems as well but their not. I Tried the led bar on my buddy's Chevy and it works perfectly fine. I even went and bought a test light for the plug. And the lights on the test plug all light up at the same time. I went to ford to see if they could try and help but.... they wanted 150$ diagnostic fee which is just outrageous. I guess my next action will be to try and hooking it up to a trailer and see if its working correctly. I'm totally stumped.

 

this is something i found on a dead thread on another site. 'My brake and turn signal lights would work, but not the running lights, unless I didn't plug in the other lights. Tried with my trailer harness and hard wired." Basically my issue but he said " I sent them an email with pictures, and within a few days they had sent me a small adapter to plug in between my plugs, and it's worked since. I don't know what makes it work, but it does. Bunch of people asked what this adapter was but he never returned to the thread xD

 

This is not a truck wiring problem if trucks tail lights work, its a trailer issue

No adapter but maybe a resistor helped if it lowered the voltage to trailer lights, depends on it the "adapter" was hooked to just the 12v wire or to BOTH 12v and ground

Some LEDs have a + and - connection and they won't work at all if reversed
Others need a lower voltage to work

Yes, I would test the trailer LED lights just using 12volt battery power NOT from the truck wires(can use truck battery), hooked directly to the lights, and then try a 9volt battery
And reverse polarity to see if the LEDs work in either direction

 

LED lights can act strange when connected with standard incandescent lights. I added strip LED brake/turn signal lights higher than the standard lights on my trailer for better visablilty. The standard lights work fine all the time, but the LED lights will only work if the engine is running. I have not tried to figure out why. The only time I need the LEDs to work, the engine is running.

 

So i hooked up to my buddys trailer and everything worked fine. So ya it has to be the lights. I'll test what u said when i wake up tomorrow and get back to you.

 

If you don't know the brand of the LED lights then you may need to change them to a "known" brand that work with your system, or at least has a place(website) you can look for trouble shooting

 

Ya i gave up on the lights and returned them. Too much of a headache to figure out why they work on other trucks but not mine. Guess ill try to find a different brand and see if it works. Thanks for all the advice trying to get them running

 

Very good thread; thank you all for the answers and the participation! This problem is known to me too and I, as a non-professional, was already going to visit an auto repair shop and leave there some significant sum of money as usual. But this thread gives me hope that I will be able to fix the problem myself. It looks like I need other interior car lights to fulfill the purpose of the old ones. I already have some installed in my car, and now I will install some additional in my trailer too. The thing that I need to figure out is how to connect them to the car’s electrical system.

 

Use fuse tap or "add a fuse", as seen here: https://cdn11.bigcommerce.com/s-za60...312329.jpg?c=2

You unplug an existing fuse, full time power or key on power, your choice, then plug one of these into that slot, this will give you an extra fused connection