I bought a used Yakima Rack and Roll trailer. The right rear tail light only comes on when lights are on, and is bright like the brakes are depressed. Signal doesn’t flash. Make try to fix, but may rewire the whole thing. Can’t find rewiring info anywhere. Any suggestions? Thanks.
On a trailer, the ground connection goes through the trailer frame, and problems like you describe are often caused by a problem with the ground. Try unbolting the bad tail light and wire brush the mounting screws, the portion of the frame where the mounting screws go through, and the lock nuts that are used to bolt the light on. You need good electrical conductivity through all of that to get a good ground connection. It’s also possible that the tail light will have a short stub of wire with a eye on the end that goes under the mounting screw, so make sure that’s clean and has good conductivity too.
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If you do rewire the trailer, you can optionally add a ground wire. This tends to make the ground connection more reliable.
Assuming that the car side is working fine, you usually can get a testing connector inexpensive to test the signals.
If the light uses a bulb instead of newer lens. They may have a incorrect bulb. Many times the bulb for the rear trailer light has 2 elements in it so one bulb will either show dim running lights and can show the brake or turn signal.
Usually the rear lights have 1 ground connection for both brake and running light. And you indicate the the running light is bright but no turn or brake on that light…
The bulb could also need to be replaced.
By all means, make sure ground connections are clean and tight, for starters (and a wire brush isn’t enough. Scrape the connection area down to fresh, shiny metal using something like a screwdriver). It’s common that fixing ground connections solves everything. That said (and some of what’s described below might be obvious to you already, but if it’s not, the info might help)…
What you describe is a very common problem for two-filament bulbs of the “old style”, which had two lead pins at the bottom of a brass cylindrical base, with two pegs on opposite sides of the base at different elevations which matched notched slots in the light-fixture housing at corresponding elevations (this is supposed to prevent installing the bulb backward but that doesn’t stop some people from putting it in backward anyway, so check this). That style of bulb is notorious for having a bad fit in the socket, and in trailer applications (as opposed to the situation in old cars which use the same bulbs), this problem always seems a lot worse (maybe due to cheaper fixtures or just more exposure to the weather). A more-modern style of two-filament bulb that has a slide-in connection is a lot more reliable, but there can still be problems with getting good electrical connections at all three contact points.
What you describe is a situation where the brake filament is energized by the parking-light circuit. Also, from what you describe, it seems that the parking filament might be energized too. In any case, the brake-light circuit (which also is the same circuit that energizes the flashing of the turn signals and four-ways) must not be having any affect at all here, or for this light fixture it’s shorted with the parking circuit.
If jiggling a bulb in the socket clears up the problem, this probably won’t be the last time you need to do that, and the best solution is to replace all light fixtures with modern ones having LEDs. If your trailer already has LED lights, it’s most likely that your problem involves bad wiring connections.
You do need to verify that the wiring is all okay, using a multi-meter (you can get a cheap one at the hardware store for about the same cost as a decent calculator). If the wiring has a problem, that won’t take long to identify, but if you see a lot of bad connections it can be easier to install all-new wiring (see below).
You don’t need to contact Yakima about a wiring diagram (and DON’T order any parts from them because they will most likely gouge you on prices for basic items you can buy anywhere). All basic trailers use the same wiring pattern. Also, they all use the same color code for identifying which wires energize which lights (or which filaments in old-style two-filament bulbs), and which wire is the ground. I could summarize this here but there are lots of internet sites and YouTube clips that explain trailer wiring, and it is very simple to understand. Any auto-parts store, or hardware-type store that sells hitches and the like will sell trailer wiring kits, as well as modern replacement trailer lights. You will need a basic four-wire kit, and one that has a very short overall length will do the job since your trailer is so short. You don’t need exactly the right wiring kit. If your trailer has side marker lights and your wiring kit is only for taillights, you can splice in the extra wires that are needed to energize the side markers. I’d recommend that approach, actually, since you can put the spliced-in wires exactly where you need them and you won’t have lots of extra wire that must be coiled up and stored on the trailer frame in bulk (messy) or cut out and reconnected to proper length (which is no easier than doing the splicing job).
If you re-wire the trailer and you have never soldered wire connections before, I recommend getting a soldering gun and soldering all connections (internet advice sites and the guy at the hardware store will tell you to cover your solder connections with heat-shrink tubing but there’s no need to mess with that. Electrical tape is fine). Hardly anyone solders their connections nowadays - they just use twist-nut connections - but the day WILL come when those twist connections fail and you’ll be tracking down wiring problems all over again, while soldered connections will still be good when your great grandchildren have the trailer. By the way, if you have a propane (or MAPP gas) torch, you can solder with that and it will be a lot quicker but you can’t do the work in close proximity to stuff that doesn’t like heat (such as soldering right next to plastic light fixtures).
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