trailer light question

[rboat]

I have a problem on my trailer lights. The running lights work fine but the right turn and brake light do not work. I have checked as much of the wiring as I can see. It is a regular flat 4 pin connector hooked up to my 97 nissan pathfinder. I tried a 4pin tester on it and it shows the led lighting up from the truck side for each operation. I am not real good at electrical stuff so any help is greatly appreciated. Thanks.

[senile1]

Did you double-check the filaments in the bulb?  The brake light and direction signal are carried on one filament and the tail lights are on the other filament.  It sounds like your brake light/direction signal filament is broken.  

[Way2slow]

First, does your truck have the trailer light adapter installed required to connect trailer lights.  If not, you will need to go to your local discount auto parts store and buy the adapter made for it.   With the proper adapter you usually only have to unplug a connecter near the rear tail lights and then plug those two ends into the adapter.    The trucks lights wire totally different than your boat trailer and the adapter is required to make the brakes and turn signals work on the trailer.

If you have the proper adapter installed, and these are old existing lights, go to wally world or some place, spend the $35 for kit with two new submersable lights with the complete wiring kit and replace everything.  The lights could be corroded and not making connection, the bulbs could be not making connection, the wiring could be bad, so to save a bunch of heart burn, it's much easier and not that much just to replace it.

[rboat]

Thanks guys, I did double check the bulbs and replaced them just to be sure. The truck does have a small black adapter box that they installed with the hitch. A guy told me those little black boxes go bad pretty often and usually give the type of problem I am having. The box is $20 and seems easy too replace, so I will start there. If that doesn't work it is off to wally world for a new lighting kit!

[Skwerl]

The right turn/ brake light is powered thru the green wire. I'd try to trace the green wire from the plug back to the rear trailer light and see if it's broken or cut anywhere. Look especially close at any connections or splices. You indicated that your LED indicator showed you have power at the plug, so the problem is not in the black converter box. You have replaced the bulb so it is likely OK. That means your break is somewhere between the plug and the bulb.

Just so you know, standard 4-wire trailer wiring is color coded like so:

Green - Right brake/ turn lamp

Yellow - Left brake/ turn lamp

Brown - running lights

White - ground

[RobDar]

what era trailer lights are we talking about here???

the waterproof enclosed style or the older exposed bulb?

since you said you changed the bulb I am guessing the exposed bulb...

[Flatfish]

If your light's bolt on to the trailer unbolt them and wire brush the mounting bracket and the back of the light real good, then reinstall the light and test it, sounds like a grounding problem if some of the lights work and some don't. A quick way to test it is turn the light on and place the blade of a flat tip screwdriver between the light assembly and the mounting bracket and turn the the blade a little if it works it's a grounding problem. Or remove the len's and take a short piece of wire, touch the base of the light socket and the other end of the wire to a bare spot on the trailer frame (scrape some paint off, shiney) also if this works it's a ground problem. Most trailer light problems are ground related and not broken wiring,

[rboat]

I fixed it. I replaced the little black box converter in the truck and that did it. I noticed that I was getting 8 volts to 0 volts on the working side blinker and only 4 volts to zero on the non working side. The 4 volts was enough to light the LED tester but not enough to light the actual trailer bulb. The shop told me these little converter boxes are full of diodes and are made to short if the trailer experiences any short or spike. This protects the tow vehicle from any back current that could damage wiring or vehicle lighting. Thanks again for the replies.

On a related note. Does anyone use the sealed LED trailer lights. They look great and are supposed to last much longer with fewer problems. I am thinking of an upgrade, but they cost twice as much. your thoughts?

[Al Wolbach]

LED lights in a word.............Great..........................Al

[burleytog]

LED's are worth every penny.