I have found my 96 XLT door ajar light on to, I go back and slam the doors, and I mean slam, when I first got it I was real easy with closing the doors as to be nice to it, but my 96 doesn't work that way, the senser switch is probably dirty, worn or something so I slam it, and the light goes out. The reason your is going out after 20 minutes is because the timer to save the battery, and when you push the alarm on the key chain it beeps is because the sensor switch senses the door is open, and probably is just not closed tightly. Try slamming the doors one at a time to check which one is the problem until the light goes out. 96 XLT is the rear tailgate one on mine. Hope this helps you under stand. My 03 had the same problem. Either a faulty or dirty/stuck sensor. First try spraying WD40 into the door cavity behind the latch. This may clean the dirt etc and allow the door or close and the sensor to be happy.
Pager, Alarm clock, cell phone, and smock alarm
Many camries have manufacture alarm system. You Camry has it, that's why it beeps when you lock the car. It sets yp the alarm system in the position ON.
5pm
Hit Mode until it gets you onto the alarm. Then hit Start to toggle between 4 different combinations of alarm (no alarm, beeps on the hour, alarm, alarm and beeps on the hour) there are two illegible wee dots in the top lcd that are supposed to say what is going on, but you will need a microscope. At least I think that is what the answer is. Time will tell.
You can get many varieties of special and unique sounds for an alarm system, from vocal sounds to the standard beeps.
It would depend on the alarm, a steady alarm indicates an engine over heat. If the engine alarm is a series of beeps, this would indicate an oil pump / supply failure.
The switch chooses the alarm type: M = Melody V = Voice A = Alarm - normal beeps
Replace the battery. That will sort your problem
5:00 pm
If you have a valet switch, just hold it in for a few seconds with the alarm off and release when it beeps or blinks the LED. You may be able to unhook the battery briefly to reset the alarm's status.
When your alarm system is malfunctioning the horn will be when the engine is off. You will need to reset your antitheft system.
usually no longer than 15 minutes