Check your ground.

 

Whenever wierd thigs are happening with trailer lights the first three thins to check are ground, ground and then the GROUND

 

Iffy plug? Check and clean all your connections.

 

Whenever wierd thigs are happening with trailer lights the first three thins to check are ground, ground and then the GROUND

Agreed!! Always been the issue when I have had problems.

 

i dont think its your ground if your brake and turn signals are both working. have you tested just behind the trailer plug when plugged up? i would test my bulbs first then use your tester and see if your getting anything in the light socket. unless you have the led lights the bulbs could be bad or the bulb or the element in the bulb socket can corrode and not make contact. you could also check the wire where it connects to the lights. if you dont have anything there then the wire is probably broken somewhere. its easy to test your ground to the trailer. just hook your ground on your tester to the trailer and touch the tester to the wire on your truck plug. keep us posted. im going to say the bulbs just are not making good contact because of corrosion. i,ve had that happen many times with the old style lights. i switched to the led lights many years ago. since then the only trouble i,ve had was the ground after using the trailer in salt water.
sherman

 

my explorer has a separate fuse for the trailer....the vehicle will be good but the running lights won't work....it is the trailer fuse....at least on my ford explorer.....but groung and spray your connections with wd-40 for better contact

 

Use dielectric grease on wire ends before crimping, run ground wire direct to battery neg terminal thru plug. after testing everything coat connections with liquid electric tape, clean all bulb connections and coat with dielectric grease. You'll never have another problem!

 

I have been a mechanic for the last 10 years and have seen this more time than I can count, 95% of the time is is a ground issue. Find the ground wether it is a wire bolted to the frame or the lights use one of the mounting bolts of your bucket simply take it apart and clean the frame so bare metal is exposed and you should be good. Also chances are good if you watch the lights while your turn signal is on sometimes the signal that your not using will blink slightly also it is just hard to notice


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Thanks guys, when i have the trailer and vehicle connected, i test the wire behind the trailer connector and it doesn't work. The vehicle plug socket when tested works. I even changed the trailer plug, but still no signal going into the trailer. The brake and turn signal wires all test good. I have a ford escape, maybe I will check if there is a fuse, but the wire from the vehicle wouldn't test ok, correct?

 

XX times 10 GROUND prblm.

 

My 2010 F-150 has two fuses associated with the trailer brake lighting. One is for the trailer light relay and the second for the lights. You should check your Owners Manual and see if you have two also. I had a very similar problem and it turned out to be the relay fuse.

 

If it was a fuse or relay then you would not have power at your plug from the vehicle


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Have u checked your ground yet like 10 other people have stated?..Its your ground causing the problem...guaranteed.