I was towing the boat home all was fine but when backing in the brakes and turn signals went out and now using test lamp, only the reverse and marker lights are hot. Nothing with brakes or turns. Worked fine since I got it. Short somewhere in trailer?

 

I've had a similar problem when the trailer wiring is shorted. Unplug the trailer and check the pins at the outlet on the rear of the truck. if everything works it's the trailer, if it doesn't it's the truck.

 

Thats what I meant, no power out of the 7 plug. All lights work on the truck, just not out of the trailer tow 7 pin.

 

well it sounds like you trailer has a short and that blew the fuse under the hood on the truck

replace the fuse in the truck, then test the rear plugs

than go to your boat trailer and look at you rear light for the source of your problem

also do you unplug the light when backing into the water?

 

The title relays blown is misleading. Relays aren't blown maybe the fuses for trailer signals. 95% of these issues are from crappy old trailer lights. Most folks don't spend a lot of time on wiring them with care. Take a volt meter and see what is grounded on the trailer side.

 

I'm going to say redfx4150 is on to something. You really should unplug before backing into the water. I had this problem a few years ago until it dawned on me the trailor lights were filling up with water and shorting out. Mark

 

well i know first hand about junk water proof boat trailer light that hold water better than a glass

but somewhere their is corrsion or a broken ground

 

12 volts battery usually doesn't short in water does it? Nothing like house voltage anyway. I bet there is a chaffed wire somewhere. Most trailer wiring I have seen is scary at best.

 

Checking this week. Box under hood points to relays not fuses.

 

[QUOTE=L8 APEX;4192556]12 volts battery usually doesn't short in water does it? Nothing like house voltage anyway. I bet there is a chaffed wire somewhere. Most trailer wiring I have seen is scary at best.[/QUOTE

12v will short in a hearbeat but the wiring would need to be chaffed or knicked like you mentioned. Personally instead of finding the problem and possibly only being a bandaid for future issues, I would pull the wiring and replace.

And for the guys who say unplug - it is not possible for people like me who have hydraulic disc brakes. I've been dunking my current boat in water for 9 years and never had a problem with a short. Bad lights yes. I took care of that and replaced all my lights with LED's 4 years ago.

 

I smear all my connections with di-electric grease and have never had a problem. I got into that habit by owning Harleys. Just foggy conditions will make those thangs start shorting.

 

Rewired the trailer. Working fine now. Thanks guys.