Dang, the eternal stop/ tail-light deliemma!
Sometimes it seems nothing works! (at least for very long).
Here are some things to think about that can help your system work, although just as sure as I, or anyone, makes a specific recommendation, someone else will find that the named approach didn't work for them!
Grounds- One of the biggest problems with trailer lights is poor grounding. It's just as important to the circuit as the hot wire. Most trailers are wired so that the frame is grounded, and all lights depend on a good ground to the frame to work. Problem is that the ground wire from the light to the frame as well as the main ground wire up front where the harness is first grounded can corrode and break up the circuit.
First thing here is to
1) solder wires as good as possible, using
liquid electrical tape to cover the joint, or
2) use quality solderless connenectors with shrink plastic sealant tubing included or placed over them, or
3) some combination of the above that you prefer to keep the water/salt away from the metal wires and fittings.
I actually "double ground" everything: all grounds are made to the frame as normal, PLUS I ground every light back to the front harness with wires. In this way, the filament can find ground back through the frame OR the ground wire. Yes, it's a lot of extra trouble to run a second return circuit, but weak, intermittent grounds through the trailer frame (especially a bolted, not welded one, are not a problem.
Weak grounds can result in the light filaments grounding back through the lamp base and then through another filament and the subsequent wiring to find ground, which then lights up the other filament and produces a nonsense light pattern that seems to defie analysis.
If the double grounds seem redundant, that's good, because redundancy is one way to fight circuit loss, which is a easy victum to any interruption when no alternate paths are available in a series circuit.
Another trick in this area, is to cross-link the tail light filaments from right, left and center fixtures as well as bring two hot wires back from the front harness tail light source to the rear of the trailer. Lose one wire, and the lights still work.
Ok, so I'm paranoid about open circuits, but my lights generally do stay on.
When we raced small sailboats, we made a "light bar" that fit across the stern/transom of the boat and contained the lights as well as held the mast when trailering. A similar light bar on a C-Dory would allow the removal of the light system before launching to entirely eliminate the submersion issue.
LED's will undoubtably be the way to go, sooner or later. The first class truck-style components originally cost about $65 each, but less expensive alternatives in the $30 range are appearing. I don't know whether their quality is up to par, though.
Another way to eliminate common problems is to build a junction box up on the front of the trailer tongue to organize and make more solid the junctions between the incoming light harness from the tow vehicle and the outgoing lines to the trailer marker lights and stop/tail lights.
The stop/turn signal lights usually only have one junction to make, but the tail light incoming wire can be split into several wires for the marker lights and various tail lights, and that connection can be a funny one without some forethought. So can a ground junction in the "double ground" system.
I like to crimp circle connectors on each wire to be connected, bolt them together with a machine screw and nut, and then coat the entire connection with liquid electrical tape, and then tape wrap it. Enclosed in a sealed metal box, this connection seems bulletproof.
Using heavy, well insulated wires for the run back to the lights is also a plus.
I used 10 gague, 3-conductor heavy duty black rubber covered extension cord wire on my last re-wire. You have to figure out a way to keep from trapping water in the space between the wires and the cover, but the cover eliminates wire chafe and the resultant shorts. The cheap, flat 4-conductor wire usually supplied with new trailers is a ready made problem for chafe in the world of sharp-cornered trailer tubing.
In another vein, WestBar, I believe, makes the sealed clear plastic bubble units that have three bulbs inside that really avoids the corroded bulb base/socket issues. These replaceable units fit in the special made red lens and base fittings made for them. I use only these or LED's.
No end to this subject! Nor no absolute bulletproof system!
But, just like the mousetrap, everyones trying to get a better one invented!
Joe.
