Monday 20 February 2017

Upgrading the headlights (sorta) on the TJ

This isn't really upgrading the lights, it's about upgrading the wiring to the headlights. Stock Jeep (CJ/YJ/TJ apparently JK) have piss poor headlights. I was recently out with my wife on a stretch of road with no streetlights, it was as if I had no headlights. Cars passing me had these beautiful bright lights and I probably could've used a lighter and a mirror
and had better output than my TJ lights.

Enter Relays. Relays a triggered by a switch, but carry far more power through the relay than a switch can handle. It's safer for your fuses and switches, and relays should be used whenever high-draw items are used.
If you check out the diagram to the left, you'll see a basic relay. In this case when the switch is closed on the input to 86, it triggers a spring loaded internal switch, which is capable of much higher amperage, to close between 30 and 87.

After reading around I discovered that Jeep routed power through the switch in the cab, and than to the light. All that extra wire causes a voltage drop, which means less power to the lights themselves. By using a relay, you can have the power go directly from the battery to the lights, and use the switch in the cab to activate the relays. Better for the switch, and better for night driving.
Octane Lighting Harness

For a really good write up, check out While I'm handy with a soldering iron, and not afraid of hacking up my wiring, I found a simple solution. That solution is the Headlight Relay Wiring Harness H4/9003 by Octane Lighting on For just over $30 Canadian, I was able to easily add relays, and I didn't have to hack up my harness in the process.

It was a nice February morning, a whopping 3C out (37F). Throwing my hoodie and coveralls on, I tackled the job.

Really easy install. About 30 minutes start to finished. Run the harness, attach to the existing grounds by the headlights, run power and zip tie it all up.

I grabbed a video of me doing the install to try something new. 10 out of 10 would recommend the harness for ease of install. Not too long, not too short, everything was soldered and had heat shrink. link for the same harness

The video is embedded below.

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