Light Leveling Switch Install for 03+ OEM HID Housings

As you all know, 03+ Celicas had the option of HIDs, which included a manual leveling switch. After almost a year after intalling the housings and having the switch sit on my desk, I finally figured out the (simple) wiring and put it in this weekend. But I can’t take all the credit — x-evil-x helped by obtaining pictures of the wiring from an 03+ Celica with the HIDs from the factory, which helped a LOT, and this thread helped a lot since the system is about the same. When I saw the pictures that x-evil-x took, I pulled my switch out and opened it up all the way to the PCB and saw the traces and soon it all came together! I confirmed the wiring by testing the switch with one headlamp and used a computer power supply to supply +12VDC and ground. Here is a video of the bench testing: Switch Testing

The end result is this:
ca617188ebe185fb66b65420d68ef626  Light Leveling Switch Install for 03+ OEM HID Housings

With the ability to do this: Video of leveling switch in use

This is how it is done:

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Please click for high-res version, for printing if needed.
Note that the pins number used are not the official Toyota pin numbers, but rather just pin numbers I used for my own sake.

A brief “how it works”: The switch takes in 12V at pin 1, ground at pin 6, and through the use of the variable resistor (potentiometer) type knob, it outputs another (reduced) voltage through pins 3 & 4. The lamp is powered by pins 2 & 5, polarity does not matter. On the headlamps, the motor has 3 pins, one is 12V power (pin 2), ground (pin 1), and pin 3 is connected to the reduced voltage output from the switch. With this all hooked up, the motors are always powered on when the switch is activated, but is stationary unless the voltage at pin 3 changes (by moving the dial up or down).

Note that the use of a relayed power source is purely optional, but I recommend using one. I did not test to see how much current both motors draw during use, so I’m not really sure if it’s needed or not. But to be on the safe side, I did use one. For parking light +, I just ran a wire to the fusebox located by the passenger side feet area, and jammed it into fuse #38 (or was it 39? Well the one that’s called tail lights).

Pins 2 and 5 are for the lamp, and so the +/gnd connection can be reversed without any affect. However, pins 1 and 6 should be wired correctly to ensure proper motor movement. Pins 3 and 4 are connected together inside the switch, so you can run a wire from each of those pins to each headlamp, or do what I did and run one, then split it into 2 once I got past the firewall, it really doesn’t matter.

The rest is just getting wires through the firewall and sticking connectors on. These are the connectors I used to connect to the tiny pins:

f080db3697e008f88f0dbdc1b843651d  Light Leveling Switch Install for 03+ OEM HID Housings
These are 0.110″ female spade quick disconnects, which have been modified to fit over the pins which are narrower than 0.110″. I did this by sticking a small flathead screwdriver into the female to loosen her up a little, then with a pair of long nose pliers, reduced the width, then flattened it down just enough to fit tightly over the pins.

Here is what the switch and headlamps look like with the wires in:

f2de44577c0fd919c54d90eb3b5de563  Light Leveling Switch Install for 03+ OEM HID Housings

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Yet another note: when you first install the switch, the motors will only aim the cutoff downwards from whatever level you have the lights at. So if you want to be able to aim the lights higher, you need to manually adjust the “zero” level (which is the highest level) higher. This is what I did, and so my “normal” level is at about number 2.5. I can turn the dial to 0 and the lights will be a little high, then turn it to 5 and the lights will end maybe 15 feet in front of my car. I am not respsonsible for you getting in trouble by blinding people, do this readjustment at your own risk!

It took a while and a few hours to neatly tuck away all the wiring, but in the end it is totally worth it! Being able to adjust the level of the vertical cutoff is great! It’s a neat little feature that makes the 03+ HID housings a little cooler to buy than retrofitting HID projectors into your halogen housings.

Oh, and before someone asks, the motors come included with the HID housings when you buy them from a Toyota parts source.

Switch is part number 84152-20050 and it fits into the square next to the window lock button, as shown above.
Alex Liang
Written June 2006

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