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Discussion Starter #1 (Edited)
There are several different techniques out there for wiring up post face-lift headlights to a '00-02 car, but I wanted to see if there was a better method. So I did a little studying of the wiring diagrams and came up with something I don't believe has been tried before. The biggest hurdle of wiring in the newer headlights is getting them to function like they do on the newer cars, which is having both the high and low beams energized whenever the high beam lever is engaged (flashing or on full-time.) This is particularly important if you are converting to HIDs, as you don't want them re-firing every time you flash the highs.

Caution: Always disconnect the battery before any electrical work

Warning: This is a modification to factory wiring, and while I took measures to make it as safe as possible, you must be responsible for your own modifications and there is no guarantee that it will not cause damage.

Parts needed: (all parts are available at Autozone, unless noted.)
H7 bulb (x2)
9005 bulb (x2)
H7 plug (x2)
9005 plug (x2)
16ga ground wire (about 8 feet)
Blue 14-18ga wire tap (x1)
Round or spade wire terminal (x2)
Solder
Heat Shrink Tube
1/4" plastic split loom
Electrical Tape
H7 Bulb Socket Adapter PN: 90075-99140 (available at Toyota dealer) x2
Parking light Plug Socket PN: 90075-60021 (available at Toyota dealer) x2

Tools needed:
Wire strippers / snips
Soldering iron
Pliers
various tools to remove headlights / bumper / frunk plastic (I won't cover that, it can be found elsewhere.)

Here is the H7 bulb socket adapter that you'll need so that the spring retainer will actually hold the bulb in place:


Here is the parking bulb (wedge type) plug socket. The pre face-lift socket will physically lock into the headlight housing, but there is interference with the plug and you will not be able to actually plug it in without these new sockets.


The turn signal is the same, no work required.

Let's take a look at the wiring schematic. To help orient you, all the terminals labeled "5" (that's the circle with a 5 in it) are located in the fuse/relay box in the passenger side of the frunk on the right-hand shock tower. DRL No 2 Relay is basically your relay for High or Low beam operation. You can see how it is defaulted to low beam, then switches to high, taking power away from the lows. We want to still allow for the switching on and off of the highs, but maintain power to the lows. So we make a splice between the solid red power wire and solid blue low beam power. The low-beams are ground switched at the BCM, so they will only be on if the DRLs are operating or you physically turn the lights on at the stalk.


This is the actual wiring of what we were just talking about. The relay box simply unclips from its mount, allowing you to turn it over and access the bottom. The bottom panel also unclips, allowing you to access the wires inside. Locate the large gauge solid blue wire and the medium gauge solid red wire. These will be spliced together using the wire tap. You will have to modify the wire tap to allow both wires to pass straight through (basically use a knife to remove any plastic that prevents the wires from going through.) Crimp the tap down, ensuring the bridge cuts into both wires, then close the plastic clamp. Tuck your wires back into the relay box, put the cover back on, and clip it back to its mount on the shock tower.


Now for wiring the actual plugs. Cut off your old H4 plug and discard. You should be left with three wires: RB, RL, RY (right) and RG, R, RY (left) Note: my left hand wires had RL instead of just R, no big deal. Connect your RB(RG) and RY to your H7 plugs. Connect your RL(R) to your 9005 plug. The other lead of your 9005 plug will run to chassis ground, this is where you'll need that wire and ring/spade terminal. There is a factory grounding lug on each shock tower in the corner of the frunk, this is what I used for ground. I soldered all the wires and used heat shrink, then covered them with the split loom and electrical tape.


Here's what it looks like finished:


And just a comparison between the new and old. I had both painted 6R4 to match the body:



So what is different about this technique: it uses the factory wiring channels for power to high and low, which means you retain your factory fuses. So you can blow a fuse independently for High or Low beam, which is safer and aids in troubleshooting. Additionally the two beams do not share the same ground, so you aren't over-loading the BCM with double the amperage it is expecting. The DRL operate as normal, and you can still wire in a DRL kill switch as I have. Everything operates just as it would on a '03+ car.
 

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Discussion Starter #2
Just an update:

Did my first night drive with the new headlights. Two thumbs way up! The beam is a vast improvement over the old style and has a nice cutoff line on the lows. I'm not using HIDs, but Silverstar Ultras for all the bulbs. Wish I had done this a long time ago.

And no issues with the wiring. Highs work with lows on and really illuminate the road well. DRLs still operate as normal unless I flip my dash switch to turn them off.
 

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Great write up!!

Two questions:

If you were to go HIDs for low beams how would you wire up the relay setup for power and would one or two relays work for each light?
 

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Discussion Starter #4
Great write up!!

Two questions:

If you were to go HIDs for low beams how would you wire up the relay setup for power and would one or two relays work for each light?
I'm not that familiar with HID kits, but why would you need a relay? I was under the impression that they didn't pull that much amperage.
 

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Discussion Starter #6
Well if it's necessary to use a relay and a battery direct power cable, I would wire the relay's switching terminals into the H7's power and ground because the car uses a combination of switched power and switched ground (for DRL and manually selected lights.) So basically on the wiring diagram above where you see the wires run to the H7 bulb, just run to the relay. Red/Yellow is ground and they come together just before the BCM. One or two relays would depend on how you route your wires and purely for convenience since you would no longer be utilizing the stock fuses as I have.

There's a high amperage power cable in the driver's side relay box in the frunk. It's a pretty heavy gauge, black with a green stripe and runs from a 100amp fuse in the engine bay. I used it for my Hella horns and IC coolant pump.
 

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Discussion Starter #8
I wouldn't use those with my wiring, you can't upgrade all the wiring because it runs through the BCM, which you can't upgrade. That's extra amperage running through some very expensive parts. 10 extra watts probably wouldn't make a huge difference, but I wouldn't risk it, plus the added heat you are introducing to the in-closed projector beam housing.
 

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where did you find the head light casing, because i have a 03' with the chrome , and i love the black look with the 03' style head lights
 
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