My First Boat - Trailer wiring problem

[thersho]

I just bought my first boat. It's a used 1993 and looks and runs like it's brand new. I bought a 7 round to 4 flat connector so I could tow the boat home after I got to test drive it. I also got one of those 4 flat checkers with the LED's so everything checks out ok on the truck. The running lights work fine, when I turn on the blinkers all the trailer lights flash. As per one of REW's posts I took out my trolling motor battery and made some leads to connect to the trailer wiring. When I apply 12 volts to the running light connector all the lights turn on. When I connect to the right turn only the right rear turns on and when I connect to the left turn only the left rear turns on. Should the side markers be on each side as well? It looks like everything is working ok, but when I plug the trailer to the truck it doesn't. It starting to look like I will not be able to use the boat for the walleye opener this weekend. Thanks.

[fshrman-r72]

It might help if you would tell us what your tow vehicle is. But if I needed to get in water right away I would find a Trucks R US or a place that installs hitches and they could fix your problem in a heart beat. I had light problem the other day and didn't know my vehicle had a converter in the rear tailight section and they checked all the fuse boxes, I didn't know I had two, one under dash and one under hood. They had a tester that could almost talk and my point is get some professional advice and have them repair this time. It will cost a few bucks but the next time you will be alot smarter. That's all the advice I can give you. Hope this helps, Good Luck, let us know how you come out.

[Trailerguy]

What I think you are saying is that all the lights work OK when you use a seperate battery and the plug from the truck checks out Ok too.
However when you put them together it goes bad. That sounds like the classic loss of ground, or the white wire not making connection.

[Bradnd]

thersho

double check to see if you have a good ground to your trailer hitch. I usually had to clean mine up every spring, otherwise I had lights blinking everywhere. I believe it's the white wire off your plug-in.

Take care,

Brad

[thersho]

My truck is a 2000 2500 Silverado. Last year I had a prodigy brake controller installed as I was towing a 28 foot camper. I don't think there is a problem with the truck, like I said I purchased a 7 round to a 4 flat connector, and a tester that plugs into the 4 flat connector and all is ok with the truck.

[therso]

Exactly, but the problem is I cleaned all the connections and used diaelectric grease to make sure I was getting a good ground. One other thing when I turn on the lets say the left turn signal and all the trailer lights flash it is a dimmer light than if just the lights are on.

[thersho]

If the ground is bad or wasn't working then when I hook up the battery to the plug the lights on the trailer should not work?

[WESLO]

Take a test light and see if the wires on the truck and trailer match up. Don't count on color matching the wires. Matching the wires work most of the time but not always. You may actually have to loosen the plug from the truck to see if the correct wire go together. I have done several trailers with the round 7 flat plugs and almost always the colors don't match. The running lights\side marker lights should only come on when you connect the brown wire to the battery off of the 4 flat plug. If they come on when you connect the turn signals there is a bad ground somewhere on the trailer.

[Bradnd]

therslo

I assume the wiring on the trailer is all original? There's a good chance you may have some brittle wires that could be shorting out somewhere. I would check all wires that are exposed outside the trailer first.
As for the battery check, I don't know if you need a ground wire from the battery to the trailer while checking each hot wire or not. I usually just use a test light for each hot wire. Most times, the problem is a bad ground connection, or a bare wire exposed. Also, pull the lense's off each tail light & check each bulb to make sure it is making contact with the metal behind it. I always take some emery cloth & shine it up, then add a little grease to the contact points.
Wiring that ages up to 10 years can start getting pretty brittle, so I would do some inspecting. If it's bad, it would be a good time to start with all new wiring.

Take care,

Brad

[thersho]

Thanks everyone, I have the problem solved. The trailer plug was not long enough to connect to my truck so the previous owner of my boat had an extention, which I plugged into my truck and the trailer plug. The problem is the white wire is not connected to both ends. One end is for hooking up the trailer ground. So I attached it to the trailer with the one that was already there. This caused the truck not to see a ground. When I connected that wire to the truck all the lights worked. All I need to do is make the trailer plug another foot longer, or find an extention that passes the ground to the truck.

Thanks for all the help.