Trailer Lights

[1ryanb]

I've read a few other posts similar to my problem, but nothing quite the same...

I have two vehicles and two trailers, let's start wih vehicle 1 and trailer 1, for some reason this combination is popping the left turn trailer fuse in the box under the hood. This leaves me with no left turn light or left brake light. The right turn and right brake both work fine. I chased all the wires on the trailer and found no problems.

With this same vehicle and a different trailer everything worked fine. Both trailers have LED lights by the way.

With vehicle 2 and trailer 1 everything worked fine.

Do I try throwing a turn signal relay at vehicle 1 (my TB) to see if that solves the problem?

 

[kickass audio]

I had the same problem on my envoy but with the passenger side turn/stop light on my trailer not working. and everything else on the trailer and truck worked 100%. I found that the fuse under the hood was popped. I knew what caused it, it was my friends old jet ski trailer that has frayed wires where it comes out of the neck on the trailer. It caused it to ground out and pop the fuse.

Something to do a good test with would be to grab a multi-meter and set it to ohms and see if you can find resistance between the wire that is for the left turn lamp on the trailer to the frame of the trailer as that is the ground. You will be required to take the left turn/brake light out of the trailer while doing this but you can at least see if it shows resistance or not. If it does then you have a short somewhere in the wire and usually on trailers they are where the wires come out of the frame at the neck. I was lucky and my new trailer for my new jet ski has a rubber grommet on all the wires where they come out of the frame and it should help protect them from getting chaffed over the years.

Have you tried to swap LED's from one trailer to the other? It could very well have a bad bulb. Also another good thing to see would be to remove your left stop light and double check for it having no wires shorting out or corroded. Also double check for corrosion on the connector off the trailer and off the truck. Another good test would be to get some jumper wires with alligator clips on them and manually put power to the trailer bypassing your truck's connector to see if it shorts out or runs fine. I strongly recommend using at least a 10a fuse in line with the positive wire when you connect it to the trailers harness manually to protect it should a short exist.

My experience was my Envoy had corrosion on the ground terminal and the others were nice and new. I cleaned it up with some baking soda and water with a q-tip and it works great now for the ground.

BTW, welcome to the forum!!

 

[Mounce]

Welcome to the Nation!

Popping a fuse normally indicates a short but it's weird that vehicle 2 has no trouble. Maybe it's a small short that's not grounding out fully and vehicle 2 just has a higher amperage fuse?

 

[The_Roadie]

Welcome! I don't see it being the flasher relay at all, but Mounce and KA both have good ideas. All is trivial to troubleshoot with a meter, and almost impossible without.

My contribution to the suspect list is a slight difference in the trailer cable ends, where the plug on the flaky trailer engages the receptacle on the vehicle to a different depth, or there are some frayed wire hairs inside a housing that touch ground because the cord dangles at a different angle? Are the trailer plug ends molded onto their cables, or do they use a metal or plastic housing that you can take apart for an internal inspection?

 

[1ryanb]

I'll try some of the things you suggested KA. I have a meter and some extra wire laying around, so I've already tried a handful of things but you did come up with a couple more possibilities.

I did try a 25A fuse in my TB, and it didn't pop, but it got REALLY hot, and the trailer light looked like it was working, but it was only about 25% as bright as it should be.

Roadie, the connector on the trailer side is molded plastic, it was replaced less than a year ago, so I'm thinking that isn't the issue. However, I can't see the wires in there to be sure. There are some butt connectors about a foot back, and I can't remember if I've checked those yet, I'll add that to the list of things to check too. Everywhere else on the trailer the wiring looked fine though.

Being in Florida water can be a huge issue here. Both days I towed the problem trailer were dry if I remember correctly, but I'm wondering if I could have a water issue somewhere too.

 

[kickass audio]

I would strongly advise you to remove that 25a fuse and put it back to the 10a fuse, you are at risk of burning the stock wire going to the trailer connection and can make for an expensive repair.

Just to double check, take the connector off the back side of the trailer plug and see if it has any corrosion on it. Being that you are in FL you have the risk of salt water getting into the connections and corroding them very badly. It all comes down to some troubleshooting with a multimeter to see the power. You can set it to volts and test the voltage at the pins coming off the truck to ensure they are working fine. Here is a diagram to show you what pinout you have at the plug on the truck as you are facing it: http://www.pjtrailers.com/images/7way.gif

edit: The pin labeled as AUXILARY + should not have any power at all on it unless you connected that red wire under your hood that is toward the front of the fusebox. You do not need to have it connected either, it is intended for accessories like battery chargers and stuff.

Also with you having butt connectors I am really not fond of them for wiring. I would strongly suggest checking them to make sure you have no strands sticking out to touch the frame of the trailer. It only takes 1 tiny strand to pop a fuse from shorting out the circuit. Have you tried to pull the wires out of the neck on the trailer? There should be a ton of wire in there, about 1.5 feet from what I noticed on my trailer. Some others have half a foot of extra wire tucked into the trailer frame.

Is your trailer for a watercraft or just a trailer like one you would load stuff up into and take it on the road? If it is for watercraft use, when you put it in the water, do you disconnect your electrical plug from the truck?