Have a 1992 Camry and the battery slowly drains over a few weeks of not starting it. How/where do I search for what is drainng the battery? Can Toyota plug in a diagnostics and find out? This has me stumped.
Also I have put new battery in and it still happens.

There's a certain amount of parasite drain in every car. If this just recently started, then you have a short somewhere. It could be as simple as a tail light bulb filament or as complex as an internal short in the alternator. There's no easy way to find it. To find a short is a slow, meticulous, time-consuming process. One way to do it is to disconnect the battery, remove all the fuses, connect an ammeter between the battery and the positive cable. Replace fuses one at a time and check the meter. When it shows current flow, you have a circuit that's on. If the circuit is not one connected to the CPU, which must always have some electricity to maintain memory, then you may know where to start looking. If a circuit shows flow, write down which one it is, remove the fuse, and continue with the process, You want/have to check every circuit. Or, you could start with the most likely places, the bulbs in the glove compartment and the trunk. Remove them and see if it still continues. While you're at it, check the filaments in the tail lights/brake lights. They sometimes short out. If a bulb is questionable, replace it. Good luck and let us know what you find. Hy