I have a similar problem with my 2000 RX300. This has been persistent for some time. The problem is an overnight parasitic drain occurs when I leave my driver's side door and lock assembly connected. When disconnected, no drainage takes place, regardless of the standing time. Lexus dealer did circuit tests and determined, or at best, reported, that the problem was the switch and recommended a $1,495.00 switch replacement. I thought that was a tad high so I subsequently located three other switches which, when tested on my car, gave the same resulting parasitic drain. Ergo, the switch is probably not the problem. If anyone in the realm of reasonable land has an answer, I would be happy to pay you for it, providing the remedy works.
