The security system for my 1999 RX300 seems to be especially sensitive. For example, the alarm will sound and the lights will flash non-stop on a windy day. The only way to avoid it is to not enable it (i.e., not lock the doors). This is fine to do when I'm visiting my in-laws---they live in a small, rural town with very little crime---but not locking my doors is something I don't feel comfortable doing here in Atlanta.

Today was NOT a windy day, yet the alarm apparently went off for at least a couple hours. I had parked my RX at the train station around 10:00AM; when I returned around 5:00PM, I found a note on the windshield saying my alarm was going off around 3:00PM. At this point (around 5:00pm), the car alarm wasn't sounding anymore. However, the battery was completely dead. The remote control on my key fob wouldn't work, the console wouldn't light up when I tried to start the car, etc. And, of course, the car wouldn't start. I attempted two jump-starts with Good Samaritans in the lot, but they were both unsuccessful. Fortunately, the guy from AAA was able to jump it and I was on my way. After that, the car operated perfectly once more.

My questions:
1. How long would the alarm have to sound in order to drain the battery that thoroughly?
2. Is there a way to decrease the sensitivity of the alarm so that small things don't set it off?

For the record, I've had ZERO problems starting the car and nothing up until this point had hinted that the battery, starter, alternator, etc., needed to be replaced. No CELs, either. The car was in perfect working order when I parked it in the lot this morning.

As a side note---and this is something I want to start a new thread about---there was a constant ticking sound around the region of the fuse box when I returned to the car this evening. The clicking occurred regularly, about two clicks per second, even though the battery was pretty much dead. The AAA guy said it was the ECU trying to re-boot and not to be concerned. Is that true?

 

Do you have an after-market alarm?

The little information on the alarm system of RX that I have is that it would sound on two condition only ..

The Alarm has to armed and door lock latch is unlocked from the inside of RX. [the hood latch would be the second condition]

There are no motion sensors or glass breakage sensors. So if some one throws a brick (while RX is armed), no alarm would sound.

So check if the lock-unlock levers physically move to full lock position. If any one of the four has limited travel, your RX would become sensitive. There could also be a bad connection in the alarm wiring.

If some one has different information, please post here.

Salim

 

There is a way to adjust sensitivity, it would have to be done at Lexus though. It's one of the options in the "C-Best" settings programmable by the dealer for the owner.

How long has the alarm been this way?

How old is your battery? If it's near the age of replacement, I'd get a load test done/health test. These car's have quite a few electronic gizmos which take quite a bit of juice. I've noticed lot's of "newer" car's will have strange issues when the battery is ready to die. Not saying it's the case here, but worth a shot getting it tested.

 

Hypervish ..If there is sensitivity adjustment, then there would be a motion detector and or frequency detector.

Salim

 

Sorry, I was mistaken. There is no sensitivity adjustment for the security system, I had it confused with the auto-on headlights. I knew there was something about sensitivity in there!

Whoops!

Here's the C-Best settings:https://www.clublexus.com/forums/403505-post36.html