How to replace your tail lights + other 12V wiring tips

Michael Borg — 3 February 2016

As you might have guessed, this old camper is pretty much as basic as they come. There’s no kitchen, no water tank and the only electrics you’ll find are for the tail lights. Yep, this old girl is just a glorified bed on wheels and, to be honest, I don’t really want to go messing around with things too much. I kind of like the fact that my 4WD is still the home for things like the water tank, kitchen and fridge. After all, it keeps the camper trailer’s Tare weight super low – under 300kg, I think.

Plus, it means I can leave the old camper trailer at camp for a few days while I tackle the rougher stuff, and I’ll still have all my gear on board with me. Okay, so maybe I wouldn’t mind a few little creature comforts when it comes to the electrical side of things. So I’ll start by replacing the old tail lights and wiring harness, then we’ll add a few more bits and pieces along the way. Let’s get to it, shall we?


As you’d expect from a 40-year-old camper, the tail lights weren’t working very well. The lenses were all faded and the actual wiring was completely cactus, too. Now, you might be wondering why I didn’t upgrade to LED tail lights, right? Well, I reckon the originals are a bit more authentic looking. Plus, I don’t have to drill new holes everywhere to install a different style of lamp.

If you haven’t replaced the tail light wiring loom before, I’ll show you the ropes. First up, you’ll need to remove the old harness but, before you get it out, pay close attention to where it runs. If the wiring threads through the chassis or any hard-to-reach places, try taping some string to the end of the wire before you pull it through. That way you can simply attach that same string to your new wiring harness and pull it back the other way through instead of threading the whole lot manually! Remember, hidden wiring is often more protected, but it’s also harder to diagnose a problem or access for repairs. So wrap it in conduit, use rubber grommets and route it away from any sharp edges or heat sources to minimise the chance of a problem down the track.

Assuming you’ve already wired up the auxiliary plug to the wiring harness, it’s time to double check which wire is which at the lamp end. Now, the wires are colour coded, so grab a test light and check each wire before you connect it to the lamp. For example, if you’re about to attach the right blinker cable, turn the actual blinker on first and check the wire is working. Just make sure the exposed wire can’t earth out on anything.

Hands down the hardiest way to join electrical wires is to solder them together and seal them in heat shrink. If that’s not an option, go for either a plug (waterproof), or crimp the terminals at a minimum.

Now look, wiring diagrams can differ depending on what lamps you have, what plugs and electrical cable you choose and what accessories you have fitted. All I can say here is to grab a pen and paper and draw up a good wiring diagram to follow. The job will almost certainly end up neater, and it’ll save you throwing tools around the yard in frustration.


Like I mentioned earlier, I’m after a simple, easy and basic electrical system. After all, I’m only really going to power up a few LEDs, charge the phone and maybe use a small inverter every now and then. So I’ve chosen to run an ArkPak with a small deep-cycle battery. These are basically an all-in-one portable power station that can be mounted almost anywhere you want. They allow the battery to be charged via solar, 240V mains or 12V, and work flawlessly in conjunction with your vehicle’s dual battery system and, to be honest, they just save you a whole heap of extra wiring.

I’ve elected to make up a simple charging cable that connects the ArkPak to the charging cable on the back of my vehicle. Then I wired up one main cable from the ArkPak to a fused distribution block. That way, it’s just a matter of hooking any accessories up like LED lighting straight to the distribution block.


  • A great tip is to leave the fuse out of the fuse holder until the wiring is complete. This helps safeguard against accidental short circuits while you’re working away, which could potentially prevent an electrical fire or the cost of replacement parts.
  • When it comes to LED wiring, always solder any electrical connections. Using standard terminals in conjunction with the small diameter of most LED electrical wire almost always results in a bad electrical connection, which only leads to electrical dramas down the track.
  • Purchasing the wrong LED lighting strip for the job is a common reason for premature wear and failure. The materials used in the construction of flexible LED strips, aren’t actually designed to be bent constantly. Over time, this will actually weaken the protective layer until it eventually gives out. If you don’t plan on permanently mounting your LED light to a hard surface, make sure you use a rigid light bar.

Check out the full feature in issue #97 February 2016 of Camper Trailer Australia magazine. Subscribe today for all the latest camper trailer news, reviews and travel inspiration.


12V wiring tail lights electrical Review DIY Outback Equipment Vehicle Safety 2016