wrenching

'99 RX300 everything is working except batteries get drained. (Note: not my vehicle)

One of the drains with the key out of the ignition is the dome light circuit. Removed every bulb, including some not in the circuit like the license plate and lower front door lights. I even unplugged the glove box and dome light switches. Found out the drain (more than half an amp) seems to be from the center LCD display which was dark. It was daytime so I should look again for glowing at night.

There is also a current drain to the ECU. Together it adds up to an amp or more.

The key allows remote entry, but not remote start (according to owner). I can test this, but does stuff turn on when the key is inside or near the car, but not in the ignition? Does the car start warming things up in anticipation of use?

There is also a huge (almost 3 amps!) drain to the A/F heater, but that stopped after awhile so maybe it is on a timer.

wrenching

I've removed the display, radio, etc. Current stays the same.

It's not the backlight.

trhs75

Hi, and welcome! I wish I knew enough to help you out; is there a short somewhere? If you pull fuses one at a time to check for an end to the current draw, you might be able to isolate at least what part of the car has the problem.