This is JUST a tutorial. USE AT YOUR OWN RISK!!! You let the smoke out of the box don't blame me!. Do not attempt if you are not comfortable with wiring diagrams, running wiring, taking apart connectors, splicing, and general automotive work. I am a mechanic with 9 years experiance with foreign cars and it look me 6hrs. All this work was done on a 1987 April of 87 Turbo Left Hand Drive 5 Speed Targa
http://www.supracarparts.com/Projects/1JZMirrors.pdf -Wiring Diagram
http://www.cygnusx1.net/Supra/Library/TEWD/MK3/ - Electrical Diagram for 1989 Supra
You need to keep track of all your wiring. If you do this like I did you're going to need 11 different colors of wiring. I had a spare engine harness out of a beemer laying around so I had enough wire and colors.
To start. I removed my center console to give me a little more wiring, for the mirror switch, to work with.
Now you need to take a good look at the wiring diagram for you car. And swap the pins from the USDM connector to the new one that came with the folding mirror switch.
You need a pick to release the lock on the JDM connector. When I compared the USDM I found the US pins don't use the lock like the JDM pins do, I didn't find that to be a problem they fit in fine. But when you put the connector into the switch after you swapped the pin you just need to make sure you push the pins in from the back side to make sure they are seated.
The Orange wire was the only one you need to reuse from the JDM connector. It is the signal wire the the module to fold the mirrors.
After I swapped all the pins I plugged in the new mirror switch to make sure the mirrors still operate correctly - Up Down Side To Side. The mirroes should work normally, if not recheck your wiring.
I worked on the passenger door next. The folding mirror control module hides in the passengers door.
The module sits in the hole in the front of the door, like the door control module on the drivers side. But you are missing the yellow grommets on the passengers side.
If you have some spares pop them in, I had a few laying around. But if you don't taking 2 from the speaker shouldn't be a problem.
Next is running wiring out of passenger door. You have to add 7 new wires. 4 for the extra 4 wires on you need for the drivers side folding mirror. 1 for the signal from the switch. And a 20amp power and a ground. I made it easy on myself and pulled the harness out, rather then messing around.
Next I swapped the wiring at the passenger mirror
On my car I ended up with 2 extra wires from the USDM, for heated outside mirrors I believe. I taped them up and pulled them back into the sleeve to get them out of the way.
After that I ran 4 new wires through the sleeve and wired them into the JDM harness to the folding mirror control module. And tied in the wiring I ran through the door harness.
Then I installed the module.
After that I took the drivers door apart and did almost the same wiring as the passengers side, expect you only need to run 4 wires out of the drivers door. Connect all the wiring from the drivers door to the wiring that was run out of the passenger. Give it a ground. and find a good power source. I haven't decided yet were to get my power from. The JDM wiring diagram say you should use a 20amp fuse, but I jumped it to the cigarette lighter and worked fine so got to do some more work and get it off the cig lighter.
Have fun be careful and enjoy