# Only 1 side of trailer lights work



## Chad Cohn (Mar 8, 2018)

For some reason only 1 side of my trailer lights are working. All worked a few days before now only 1 side. Tail lights and blinkers are good but when the lights are on only the left tail works. Preliminary inspection and I cannot see anything that just screams at me. All wiring is "clamped" to the trailer and I haven't enough day light to really pull it all off. Any suggestions before I really dig in? I checked with both of my trucks and it is the same with both so it's not a vehicle issue.


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## topnative2 (Feb 22, 2009)

check the plug on trailer .......shoot some wd40 in plug back together and wiggle the plug......then wiggle the wires behind the plug??????

are u using an adapter?


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## FishWithChris (Feb 6, 2019)

likely a bad ground? I'm dealing with the same thing with mine right now. Everything worked great until trailer got smacked in the ramp lot and then I've been chasing the right tail light being out ever since.


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## crboggs (Mar 30, 2015)

Check the grounds on both lights.


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## Capnredfish (Feb 1, 2012)

Little confused. Did you mean brake lights and blinkers are good? Tail light is out? A 12 volt test light or even better, a digital multimeter is your friend. Keyboard can’t fix it. But determining where power or ground is interrupted will locate the problem. There are only 4 possibilities if you ruled out the vehicle. It’s either the wire/plug, a connection, lightbulb/socket or LED assembly.


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## Chad Cohn (Mar 8, 2018)

Capnredfish said:


> Little confused. Did you mean brake lights and blinkers are good? Tail light is out? A 12 volt test light or even better, a digital multimeter is your friend. Keyboard can’t fix it. But determining where power or ground is interrupted will locate the problem. There are only 4 possibilities if you ruled out the vehicle. It’s either the wire/plug, a connection, lightbulb/socket or LED assembly.


Tail lights & blinkers work but running lights do not including the tail light on the side that is out. Which is super weird to me. No adapters just straight plug into vehicle. I should have some time today to look everything over more thoroughly. I'll use the volt tester that I have, short of that if I can't figure it out I will just replace the lights. To my knowledge these are the original lights that came on the trailer and it is a 2010. Thanks for the insights.


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## SomaliPirate (Feb 5, 2016)

Just nascar it. Left turn only!
I'd start with simplest stuff first. As previously suggested, clean the plug with some spray electronics cleaner and put some dialectic grease on it. I don't think its bulbs because multiples are out at once.


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## hunterbrown (Feb 17, 2014)

Chad Cohn said:


> Tail lights & blinkers work but running lights do not including the tail light on the side that is out. Which is super weird to me. No adapters just straight plug into vehicle. I should have some time today to look everything over more thoroughly. I'll use the volt tester that I have, short of that if I can't figure it out I will just replace the lights. To my knowledge these are the original lights that came on the trailer and it is a 2010. Thanks for the insights.


Check the trailering fuses in the fuse box of your truck.


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## Chad Cohn (Mar 8, 2018)

After finally having some time to trouble shoot, I found that a wire had broke. The trailer has a swing away tongue and when I had swung it away it broke the wire. Repaired the broken and now it's working correctly.


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## Keywester1 (Sep 9, 2014)

Am i the only one that gets so frustrated with trailer lights that i just re wire the whole trailer everytime...


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## Chad Cohn (Mar 8, 2018)

Keywester1 said:


> Am i the only one that gets so frustrated with trailer lights that i just re wire the whole trailer everytime...


I was close believe me but I just happened to find it and luckily it was easy to fix.


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## SomaliPirate (Feb 5, 2016)

Keywester1 said:


> Am i the only one that gets so frustrated with trailer lights that i just re wire the whole trailer everytime...


I beat a tail light with a flip flop once and it actually started working again.


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## lemaymiami (Feb 9, 2007)

A quick tutorial about the standard wiring that comes with most trailers... First off the stuff is rarely the tinned copper wire you should have for a salt installation - and it's usually only 18 gauge (pretty thin, flimsy wire...). The four colors you usually see on the wiring harness break down as follows... white is the ground wire (and the very first place to look if you suspect a ground issue...). Brown is the wire that powers all of your tail lights and side lights... The green wire is for your right side (curb side here in the USA) brake and turn light, and the yellow is for your left side (road side) brake and turn light....

Knowing which wire does what is a start when trouble shooting trailer wiring.... and yes, if you buy a used trailer - lord only knows what wiring setup is in place... Trailers that have the wiring on the exterior of the frame are much easier to work on than trailers with the wire running up inside a closed channel or tube...

The last time I had my trailer re-wired (courtesy of Capt Jorge Valverde - a very skilled guy...) we ran tinned copper 16 gauge wiring... with solid adhesive lined heat shrink terminals at each point.... a very solid installation.


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## Bryson Turner (May 3, 2017)

Chad Cohn said:


> After finally having some time to trouble shoot, I found that a wire had broke. The trailer has a swing away tongue and when I had swung it away it broke the wire. Repaired the broken and now it's working correctly.


Same exact thing happen to mine


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