Car Alarms: Lexus alarm problem, lexus rx300, 1999 lexus rx300

Question
QUESTION: My 1999 Lexus RX300 has started alarming periodically when sitting in the garage, unlocked and I open the driver's door.   Any thoughts or recommendations?

ANSWER: It's an after market system from your description.
Probably dealership installed when
it was purchased originaly.

The shock/impact sensor seems the culprit here.
It's likely to be found under the dash area, blinking
when anything taps on the underpanel.
Locate and either unplug or turn down.
To simply disarm it, locate and use the
valet/overide switch.

To start, look under the dash area for a button or,
a toggle switch. When you locate it, turn on the
ignition key, press and hold in the button (little
spring loaded micro button, red or black possibly)
until the alarm chirps 1 time. This should over ride
the system, and only the keyless entry part,
if installed, would still be operating.
The LED (light emiting diode) light in the dash
should also go on solid.=VALET/OVERIDE

This stops the alarm except for the keyless
entry if installed. The next step is to
either remove the alarm or, try to identify,
and get new remotes for it.

But once in Valet mode, it will allow the car
to start and operate like there was no alarm at all.

Let me know how it goes.

ALARMTEK
CARALARMMAN.COM

---------- FOLLOW-UP ----------

QUESTION: Aftermarket?  Doesn't seem right.  Appears to be built right into the dash -- says "security", has blinking red light when key is removed, matches all the other dash board items.  And the key that controls it is a Lexus key -- with lock, unlock and alarm/panic buttons.  The only thing that indicates aftermarket is the fact that it's not listed in the owner's manual.  What do you think?

Answer
Hmmm, ok, the alternative is that it's got a
faulty door sensor.

The factory system is also the door lock
mechanism. The 2 are part of one system.
To disarm it, either turn the key in the door to the
left to disarm and right to unlock, or you would need
to have the factory remote to disarm it.

It might be how you use the key when entering, or it
would detect battery drain and set off the alarm possibly
due to a bad or falsing door trigger (s).

Try to always go left/right to disarm it.
That's key to these systems (pardon the pun!)

I think that might be the cause of your sporatic
arming actually.

A.