Troubleshoot Trailer Wiring - Left Signal and Brake Lights Not Working 

Thank you. This is a very logical way to help figure out issues wit hthe lights.

I would have never thought to check fuses. Thanks big help

you're better than my local boat repair shop

Thank you. Mine was also just a bulb issue. After I checked all the wires and fuse and cleaned everything.

Thank You Thank You Thank You. Replaced the light bulb ,and wow. Like you said. The bulb didn't even looked bad.

Thanks for the pointer on the light bulb. I just replaced the 4 connector wiring on my 2000 GMC Jimmy. The old connector was corroded up, and then I found that the crimp connectors that hooked that wire to the wiring that came with the vehicle were corroded up too. I replaced that and used an LED tester similar to yours. Left and right turn signals worked. However, the right turn signal on the boat trailer doesn't work. Nor the brake light on that side. I will check the bulb tomorrow. I was thinking maybe it just wasn't getting enough voltage. Hopefully, I will luck out and it will just be the bulb. However, I had a separate set of lights that you can attach to a trailer with magnets and those didn't seem to be working either. So, probably it's some other problem. The wiring from the vehicle had 6 wires. Two were taped off and not used. I think my dad did that when he wired it up 20 years ago. As far as I know, they aren't needed as the signals were working before. I'll have to check the fuses. But, the LEDs flash on the tester. So, I don't know how it could be that. Probably, it's a bad connection somewhere.

Thank you for taking the time. Great learning experience.

Thnxs!!

Thank you so much, Sir, for sharing.

BTW, a tip on cleaning up the connections. I ran across another video where someone recommended using a "bore brush" to clean the female part of the connectors. It's a little wire brush that's normally used for cleaning gun barrels. I tried it on mine, but, it was too corroded. 22 caliber seemed to be the correct size. I also tried using electronic contact cleaner, but, it didn't seem to do much.

Thank you larry, this made me do some thinking

They make a nice cheap relay tester now, works great.

Video was great. Thanks

Thank you very nice

Very helpful...thanks!

awesome job

bad ass boat

Very helpful! Thanks for being reasonable ;)

Thanks for this!

Question. i have an 02 Dodge Ram 1500. My 4 pin flat connecter on vehicle for trailer works fine. EXCEPT THE RUNNING LIGHT. My 7 pin connector on vehicle for trailer works fine. EXCEPT THE RUNNING LIGHT. What do you recommend? Thanks.

very helpful

Awesome video!

Very informative thank you

Thank for sharing the video Landry, I have a problem with my left turn signal and LH flasher, running lights work on both sides, but no LH turn signal nor flasher, truck is good, I got power in the plug for turn signals, any suggestion on what to check? thanks again

my wires are all taped up . fricken mess.

Thank you it was a fuse.

What if I have LEDs? My left side running lights are working but no brake no blinker. The right side all three are working

What if my driver side lights blinker work but not the brake light. Everything works except for my driver side brake light.