Wire a trailer with seperate (turn/brake) lights for use as combined lights too

Yes the title might seem confusing, but so is my mind.

The story: recently bought a Roll-A-Home trailer, it has a 5 conductor system on it for lighting, separate tail brake and turn signals. My previous trailer had the combined turn tail and stop lights like most do. The ST's have a separate system and I had installed a 5 to 4 wire adapter. 4 wire being the most common trailer plug.

The new trailer needed to be re-wired. The previous owner and I think the factory had set it up with a four wire plug, but the wiring was not standard. The hots were all the plugs wires, the neutral was picked up through the hitch ball. Not an acceptable solution.

I could have re-wired the trailer to just use a standard four, remove (or just not use) the amber turn indicators on the trailer. But I felt like I was losing a little visibility, plus I woudl rather remove the adapter from the bike then some bright lights from the trailer.

It would seem an easy solution to re-wire my bike, remove the 5-4 wire adapter and wire the 5 wire to the trailer direct. But then it provides the problem of not being able to tow the pop-up trailer with the car, as it has a 4 wire plug.

I could add a 4-5 wire adapter to the car, but then it's just more expense and an unneeded piece of gear.

I did convert the trailer from the typical 1157 dual filament incandescent bulb to an LED set up. Found some nice oval assemblies I could install inside the original OEM housings. Pretty slick and bright as they need while only drawing a lowly 0.25 amps each.

With a bit of late-night creativity and a few $.05 diodes, I came up with my final solution. Put both a 5 wire and a 4 wire plug on the trailer. Then it could be towed with either vehicle and if I happen to sell it in the future the new owner won't worry about wiring their bike in any special way.

When in 5 wire use mode, the tail, stop and turn lamps are all working as designed independent, with an amendment, the turn signal will flash both the amber and the corresponding side red brake light. If you apply the brake, it will override the flash and make the brake light solid. You could eliminate the two diodes at the bottom of the drawing if you do not like this feature.

When in 4 wire mode, the amber turn signals are not used, the brake/turn lighting is all handled by the red lights.

Clear as Mississippi mud?

I totally understand what you are doing there. I've thought of doing as you have done for my ST (before I sold it with the hitch) with a few diodes and relays but decided "why" change what is natural to the vehicle. Cheaper and less effort to simply add a few amber lights to any trailer that is missing them IMO.

Actually all the trailers/campers I've looked at (most of the known brands for mc use) come from the factories with 5 wire systems. This is the native state of almost all bikes and most (if not all) non-American cars. The 4 wire thing is an American convention. Therefore I do understand wanting to do this if your 4+wheeled vehicles are all American branded and you intend to pull the trailer(s) with either bike or car. I prefer the 5 wire since it's easier to wire up and less components (adapter) to fail. I've had 2 campers now that were modified by old school bikers to 4 wire to varying degree of quality (usually with bare wires twisted together and covered with electrical tape only!). I've returned both to 5 wire. My Toyota is what I initially towed the last camper home with and I had to add an adapter for the cobbled together 4 wire connector until I could restore it to 5 per the factory. My Toyota is also naturally a 5 wire system so removed the adapter when not needed. I have both on the Toyota, using 2 connectors. one connector from the adapter and the other 5 wire one before the connector.

Oh, and I totally agree that using the trailer frame or hitch ball for ground is very unreliable at best.

Updated the schematic. Someone asked about it handling incandescent lamps.

rjs987 said:

Actually all the trailers/campers I've looked at (most of the known brands for mc use) come from the factories with 5 wire systems.

Click to expand...

Interesting side note: in Europe all trailers have either 7 or (newer) 13 pin connections... ;-)

http://www.zoro.com/reese-tail-light-converter-78016/i/G7569256/?gclid=CjwKEAiAp_WyBRD37bGB_ZO9qAYSJAA72Ikg4_7TP14un6PGrCLdNVHFNFTFJiUp4oV0ys2g9pjOyxoCKjHw_wcB&gclsrc=aw.ds

Anyone tried this? I have to use them on my Jeep because the stock system doesn't handle trailer lights well. Basically, all the power is fed from the tow vehicle battery, you tap the running, brake and turn signals(under the seat on the ST), the converter only uses a signal from each tap, meaning there is not a large amount of current draw from the stock wiring, the power is pulled direct from battery. I've used these with incandescent and LED bulb systems. I've almost got the missus convinced to let me get a tag-along for the 13, it would give us enough room for her stuff on weekend trips..........
They wire in pretty easily, of course, on the Jeep I had to run a wire from the engine bay to the back.....

You might want to check with someone on the legality of both the red and amber turn signals flashing at the same time. All the tables I can find show red or yellow is acceptable. Most LEO's probably wouldn't give it a second look. But why give that one guy a reason to have a chat with you.