I have a shorelander trailer that will occasionally short out the 20 amp fuse in my truck. I replaced all the wiring and lights last year as I was having this same problem. There is no rhyme or reason to it. I could go a couple of months with no problems then it happens. I unplug the lights whenever I put the boat in the water. Has this happened to anyone else? Any suggestions?
You might have a dead short where the wiring leads frome your rear wire harness to your trailer connector on your truck.
Gator Hunter
what year truck? what type of truck?
Gundy
Had same problem on my shorelander. Found insulation on fender marker lights rubbed through where routed over spring bracket where wire goes from frame to fender. Mel
I too suggest taking the time simply trace out all of your trailer wiring to discover where the wear or breakage (of the sheething) is occuring and repair.
You guys are fast. The truck is a 96 Blazer. The reason I am pointing to the trailer itself is because I have utility trailer and I have never had a problem with those lights.
THESE THINGS CAN ALWAYS BE SO MUCH FUN 
. SO MANY PLACES TO LOOK!! WHEN YOU REWIRED YOUR TRAILER DID YOU DO A GOOD JOB ON YOUR SPLICE JOINTS ? WHEN I WIRE A TRAILER I SOLDER MY SPLICE JOINTS AND THEN MAKE SURE I WRAP THE WIRES REALLY GOOD. SHRINK WRAP IS THE BEST STUFF. I WOULD START WHERE THE PLUG IN CONNECTS TO YOUR TRAILER WIRE COMING FROM THE BACK. ALSO I WOULD GIVE THEM DARN CLARENCE LIGHTS A REALLY LOOK OVER. BIG TROUBLE COMES FROM THE SMALLEST PLACES WHEN IT COMES TO TRAILER LIGHTS. MAKE SURE YOUR GROUND WIRE IS NOT BUMPING INTO ANOTHER WIRE. THIS CAN BE THE DEAD SHORT MENTIONED IN SOME OF THE OTHER POSTS. THAT IS WHAT YOU ARE REALLY LOOKING FOR. ONE QUICK THING TO DO IS TO LOOK FOR FEED BACK FROM YOUR TRUCK TO TRAILER. IF YOU TURN ON A BLINKER DOES THE OTHER ONE HAVE A REAL FAINT FLASHING TO IT OR DOES ONE OF YOUR CLARENCE LIGHTS VERY DIMLY BLINK. IF THAT IS HAPPENING YOU HAVE A GROUNDING PROBLEM. HOPE I DIDN’T CONFUSE YOU.
GUNDY
Boy does this bring back some bad memories. I had an S10 that would blow fuses when I trailered my boat. I rewired the whole trailer and still had the same problem. I could trailer the boat behind my van and didn’t have any problems. I suspect that the used S10 I bought was in an accident and that something was messed up in the wiring 
I’m not much of a mechanic so I finally sold the truck. 
man, what a guy will do if he can’t get his boat to the water…. 
I used to compete car audio.. (10 years ago before it became annoying – and when I was much younger). In the process I’ve rattled and rubbed my way to 100’s of faulty power wires.
20 Amps is a huge fuse to be blowing on trailer lights. Short answer is that you have a positive wire occasionally touching ground. It would be pretty damn odd to have a loose ground blow a fuse…. I wouldn’t start diagnozing the problem there. Check over all of your positive wires on the trailer for insulation rubbed off/cracked in-line to the lights. Also, if you have original Shorelandr’ lights check the plug-in backs for built up debris. If all looks good, pop the lenses off your lights and look for an internal light problem where a hot wire it touching ground.
You should be able to test all of this with a Fluke (or similar voltage meter) without blowing fuses. Set it to DC. Place one end in your harness on the hot. Run the other end (you might need to use sacrificial wire) to the hot on the light. Make sure these two are connected WELL. You will see the meter at 0.0 Next lightly pull and/or hold the wires a bit at different angles, pausing a bit at each one. Assuming your Fluke connections are WELL done, it should stay at 0.0 When you will see the voltage number float from 0.0 (2.6 to -1.4 to 0.6 to etc…) you have found your bad wire.
A few other notes, I would suggest placing gromits on places where wire enters the inside of your trailer and flex-loom everywhere else. This will protect your wires while preventing corosion and insulation breakdown.
One more note on soldering.. if you don’t have a soldering iron or don’t have time to solder a small trick of the trade:
1. Don’t use butt connectors.
2. Get the right sized crimp caps.
3. Connect your wire(s) using the crimp caps.
4. Grab your wires below the crimped connection.
5. Zip-tie the wires together 2 inches below the crimped caps.
6. Snip excess ziptie.
7. Place shrinkwrap over cap and wires to zip-tie.
8. Heat and shrink
9. You’re done!
This has a few advantages.. easy off and on with little wire loss, it’s fast and not dangerous 
, still can use tape or shrink wrap, and best of all when you pull on the wires (one in each hand for example) you put ZERO stress on the connection. All of the stress is located at the zip-tie. This creates a stronger and longer lasting connection than any kind of connector or soldering.
My 222222 cents, (sorry for the length)
J
Very good info -=J=- . It sure is nice of you to take the time and post some of your past experiences here.You no doubt saved some people some time and money
I had the same problem and went through several fuses in my truck. Shorelandr finally agreed to pay to have the entire trailer rewired, despite being just out of warranty (I had a long line of electrical problems documented at the dealer leading up to the rewire). I haven’t had a blown fuse in over a year now but I still go through new bulbs like popcorn, despite unplugging the trailer at the ramp.
I’d be willing to bet that the problem is occurring at the point where the side marker lights (Yellow lights) are spliced in.
On my last s’lander, I had tail light problems to no end. Finally pulled all of the wires and I could not believe the crappy splice job that the factory did. The wires were corroded and exposed. The corrosion caused intermittent power loss to all of the rear lights.
It’s the first place I’d look…..
Jon J.
A WELL WRITTEN REPLY. ONE OF THEM YOU BEEN THERE DONE IT KIND. 
A huge thank you to all who have taken the time to respond to this. I get the feeling everyone understands the frustration of wiring. I am new to the board and you guys are a great resource for information. I’ll be staying at Evert’s in October for a few days of fishin. Hope to see and meet some of you. Thanks again!
Hey Jon, Crappy wiring jobs aren’t limited to S’Landers.
My EZ Loader developed a problem when I broke one pin off the connector. In stripping the wires back to put a new connector on I couldn’t find any wire that wasn’t corroded. It was corroding from a side marker splice all the way up to the connector ~7′-8′ Now I get to rewire my trailer.
Ferny.
I am dealing with the same problems right now. I have a 2002 F-150 and have blown the fuses 3 times this year. The only lights that are affected for me is the running lights. I still have brake and signal lights. The confusing thing for me is that this doesn’t happen with any other vehicle and never happened on my previous F-150. I’ve traced a lot of the trailer’s wiring and can’t find any problems. I taken my splices apart and re-done them and it still happens. Any other suggestions? Could it be something in the truck?
Crossin’eyes,
I’ve been a Ford truck guy throughout my life and while my experiences with them are almost all good, one weakness in Fords is wiring and wiring harnesses. They’re notorious for this. If you’ve got anyone else to test with, hook it up to another Ford or Chevy/Dodge/Whatever…………..and see if the symptoms are the same. If nothing changes, it’s still in the trailer……………but this one sounds like it may be the truck. Try a swap/compare and see what it shows you. If you don’t know who to ask, I have a Chevy Blazer to compare against if you’d like to make the time. LMK!
Ken
Hey Kid.
Way ahead of you. Hooked it up to my dad’s van and no problems. That’s not to say that it couldn’t be in the trailer and happens when you drive over a bump or something. Like I said earlier, it has done this 3 times this year. I’ve probably pulled my trailer 30 times this year so my success rate is high! 
i guess I’ll just keep a pocket full of fuses handy until the problem becomes more obvious.
You must be logged in to reply to this topic.
