Tom,

I believe it is common for both light assemblies to have a ground, ie. right
and left side grounds.

I just replaced my expensive Wesbar (?) incandesant tail lights with
relatively cheap WalMart LED tail lights. During the process I found that
each lamp had a ground wire with a ring connector for the ground. The old
lamps were the same. When removing the old lamps I found that the ring
connector was attached to the trailer rail by the lamp's mounting screws.
There was a large amount of white powder all around the drilled holes for
the lamp mounting screws where the ground wires were connected. I used some
sandpaper to clean up the area before mounting the new lamps.

The OP could easily check this on his/her trailer.

A continuity tester (ohmeter) would be my choice of test equipment to
isolate any possible trailer wiring fault. BTW, WalMart sells an
inexpensive trailer wiring harness tester. WM and BW have one for a bit
more $.

Butch
"Short Wave Sportfishing" wrote in message
...
On Thu, 15 Mar 2007 13:33:10 -0400, "Eisboch" wrote:


wrote in message
news
On 15 Mar 2007 03:31:06 -0700, wrote:

Maybe one of you trailer boaters can help me out. I've got an
intermittent problem with my trailer lights - either one side or the
other will light (tail lights and side marker lights). This is
intermittent - sometimes both sides will light. I put a test light on
my truck's electrical input - that doesn't seem to be the problem Any
suggestions on where to start troubleshooting?
Thanks much.

Grounds can be a problem but don't ignore that cheap assed connector
most trailer lights hook to the car with.
Trailer lights always seem to be trouble if they are out in the
weather and dunked in the water.. I have mine on a 1x4 that I keep in
the garage and I bungie it across the back of the boat when I tow (or
just to the trailer if I am going "bareback"). The wiring is SJOW
cord, not that zip lead the trailers come with.


I agree ... mainly because I am not so sure the OP's problem is a ground.
Usually there is only one, common ground connection to the trailer. Since
he stated that either one side lights or the other ... sometimes both ...
it would seem to indicate that he has a ground connection.

Betcha his problem is in the connector plug.

Good point.

Although on my Ranger trailer and on othe Loadright Princecraft
trailer, both sides have seperate grounds.

Why, I don't know.