Reversing headlight polarity

[FMuscle]

Hello all. Some of you may have seen some pics of what I did last weekend in my build thread:

Yep I did a major wiring cleanup of the front harness, removing every unneeded wire. And while I was there, I decided to fix most of the Toyota common issues with headlights, issues happening when one wants to upgrade the lighting.

Most common are:

1. HID not working properly, only on dipped/only on high, Flickering, etc.
2. the high beam indicator not working, either on HID or when adding a relay to keep dipped on when using high for increased output.

These problems are caused mainly by the negative control of the headlamps, i.e. the switch is on the earth side, and positive is common.

Reversing the polarity to a switched positive solves all this, and this method maintains the high beam indicator circuit integrity. Bonus, reduced wiring lenght -> reduced voltage drop.

I have a separate fuse box for headlamps in front of the main one in the bay. It was easy to open it up and trace back the wires.
There's a red and a red/black, both positive from the LH/RH fuses. Cut them. The side going to the headlamp becomes earth, the side from the fuses powers the relays, pins 30 & 85. (see below)

In the harness, you'll find two red/white and two red/yellow. Cut them.

Take the red/white pair on headlight side, connect together to pin 87 of one of the relays. Use one of the red/white car-side (or both if you don't want a wire hanging loose) and connect it on pin 86 of the relay.
Repeat the above with the red/yellow wires and the other relay.

With stock 60/55W H4 globes you don't need to upgrade the 10A fuses, but higher wattage may require it.

Now ready for any headlamps upgrades you can throw at it. FYI, I tried to make it easy to remember, I put the "LO" function on the "LH" fuse...