Chevrolet Repair: Electrical/ Trailer Wiring Harness, trailer wiring harness, hitch ball

Question
Hi, have a 98 Chev. S-10 4.6L V6. I wired the truck for an older boat trailer that had a 3 prong connector w/ground (i.e. Running-brown wire, Lft Trn-Yellow Wire, Right Trn-Green Wire, and Ground-White).  That worked good.  Got new trailer for boat. 4 prong connector w/ground. The last prong is blue wire for reverse lights to release a valve on trailer. Found the light blue wire that runs reverse lights hooked it up on truck.  Everything on truck with multimeter checks out.  When you plug trailer in it blows the L/H running lamp fuse (10a) in engine compartment.  Question: Can I put a 15a fuse in place of the 10a w/o burning anything up.  Or does the truck have a reverse/short/ground (or trailer) that is causing this.  Can't figure this out both trailer and truck look wired correctly what am I looking for?  Thanks for any help. A.J.

Answer
Don't use a bigger fuse.
Remove that blue wire connection.\
All you need is the brown to brown, yellow to yellow, and green to green, and a ground.
Some people don't use a separate ground, depending in stead on the hitch ball to supply the ground. Those are the trailers you see with the lights constantly dimming, and acting funny when you are following them.

I don't know what kind of valve on the trailer you are talking about.

My guess is the blue wire is the ground.

Van