Click pic to see
Here is a wire diagram that will help people build their own integrated wire harness that combines both HID and leveling switch functions. It requires the pulling of one wire through a firewall grommet to the interior switch. Connector part numbers are assumed to be correct, but have not been verified as of posting, so please verify the parts before you order! Pin numbers used in this diagram are not the official Toyota pin numbers.
As you can see, the design of this schematic combines the traditional relayed-HID wire harness with the existing leveling switch wire harness found on this forum, but integrates them into one harness, reducing redundant wiring. The leveling motor connector has 3 inputs: +12V, Ground, and variable voltage. In the old leveling switch schematic, I had called for an independent +12V source via relay, but now have tapped this from the +12V source to the HID, reducing wiring. Grounds for both motor and HID are also combined, since they are at the same physical location.
Inside, the switch itself needs a +12V source and ground. The +12V source is used for both switch illumination as well as creating a reduced voltage to trigger the motors. This reduced voltage wire (pins 3/4) needs to be connected to each motor, and hence needs to pass through the firewall. I suggest installing a weather resistant quick disconnect on this wire to make installation and removal easier. Place this disconnect in the engine bay before going through the grommet, for easy access.
As for the termination pins themselves, there are two options (that I know of): 1) purchase genuine Toyota wire pigtails, and 2) purchase a few Scosche TA02RB reverse stereo harnesses and extract the pins from the plugs -- they snap right into the HID/switch connectors. I like option 2 because it is a lot cheaper and easier to get than option 1. The only downside is they do not come with rubber gaskets to weather seal the plugs. What I've done in the past was I injected some RTV silicone into the holes after inserting the pins. This only applies to the connectors residing in the engine bay -- this is not necessary for the switch connector.
Please post your comments, suggestions and success/failure stories after using this diagram, so I can update the schematic if needed.
Since I am no longer in possession of the Celica, my participation in this forum has and will be limited, so please excuse any lengthy delays to responses. PMs are the best way to reach me, but please read the next line before PM'ing me.
I will NOT build and sell you this custom wire harness, so please do not ask.
Thanks and good luck everyone!
Edit 1: Here is the link to the original leveling switch wire diagram: https://www.newcelica.org/forums/showthread.php?t=235033