1999 Lexus LS400- Passenger's side rear view mirror does not adjust electrically. Driver's side works fine. New mirror (original had a cracked housing), and new switch (returned when it did not fix the problem). Vehicle has an auto focus down feature when the gear selector is shifted to reverse. Both mirrors lower and then return to theor previous position as the selector is moved. Wire colors do not match from the switch to the mirror, so I suspect a control module in between.
Is this a known common problem? If there is in fact a module, where is it located, and what kind of signal (straight DC power/ resistance measurement, or digital encoding) runs between the switch and the module? How can I check it to verify the status of module? Everything else on this car is extremely expensive to repair, I have no doubt this will be as well.
Thank you for any assistance you can offer.
WM

Optional Information:
1999 Lexus LS 400 V-8

Already Tried:
Activating the mirror using the reverse position feature. Stopped when i determined ther was a control module in between the switch and the mirrors