So confused! Need trailer help

TTk91

Recruit
Joined
May 14, 2011
Messages
3
My trailer running lights do not work! Brake works, signals work but running lights (brown) cable doesnt work. I already rewired the entire trailer, new wires, new connectors new lamps but still the same problem. So I measured the amount of volts in the female connector when the lights were turned off (in the vehicle) and it read 12 volts. when i turn my lights (in the vehicle) on it reads about 8 volts, and when I plug the trailer in and I check the voltage it reads like .33 at the plug. Spend my entire day on it and couldnt figure out what the problem is. Im plugging the trailer into a 99 jeep grand cherokee. Any tips?
 

boat1010

Senior Chief Petty Officer
Joined
Mar 10, 2009
Messages
781
Re: So confused! Need trailer help

Most trailer light problems is the ground.. Take off the ground wires and sand down to good metal and put it back together. It the electricity doesn't have a path to get back to the battery it does some very strange things.
 

201Liberator

Recruit
Joined
Mar 22, 2011
Messages
5
Re: So confused! Need trailer help

Had the same problem with mine, my trailer has a removable front for storage. The problem was the ground for your lights is grounded there, run the ground straight to your plug. That fixed my problem
 

TTk91

Recruit
Joined
May 14, 2011
Messages
3
Re: So confused! Need trailer help

I thought it was the ground too, but I have a ground cable run to each individual light. plus i plugged my jeep into another new trailer where I am certain the wires are good and it did the exact same thing. Im thinking its a fuse or a relay or something in my SUV. I also have an emergency tow kit such as this http://www.kmstools.com/be-12v-magnetic-towing-light-kit-10820 and it still has the same issues. I have no idea where to start looking in my truck though.:facepalm:
 

sublauxation

Lieutenant
Joined
Oct 13, 2008
Messages
1,317
Re: So confused! Need trailer help

I'm guessing you already checked this but my Ford has a fuse for each turn signal. Otherwise go throught the fusebox and check resistance through each fuse. It's quick, easy, and you never know what you'll find. I had problems with my dash lights and found one fuse that was half toasted.
 

TTk91

Recruit
Joined
May 14, 2011
Messages
3
Re: So confused! Need trailer help

I figured it out! Thanks for the replies. Oddly enough, the supposed circuit protector box that came with the harness i bought for my jeep was restricting the amount of voltage that could pass through to about 8 volts. bypassed the box and there was light! Now I just have to be real careful to remember to unplug everytime before letting the boat in the water!
 

Sixmark

Master Chief Petty Officer
Joined
Jul 11, 2010
Messages
890
Re: So confused! Need trailer help

Always, always, always check the vehicle first as it is the source of power for the trailer, there have been several people on here recently rewiring trailers, and replacing lights, only to find out it was the vehicle each time.

Lighting circuits on newer vehicles are not as basic as they used to be 20 years ago many now include seperate fuses for each individual bulb on the vehicle which will create headaches when trying to diagnose a trailer.
 
Top