Ls460 Alarm Going Off On Its Own

[denslexusgx470]

Has anyone ever had the issue of the alarm (factory, nothing aftermarket) going off on it's own without any forced entry? It's happened to me twice on two different occasions in the middle of the night (so annoying). I do not have enough garage space to park the LS inside my garage so she sleeps outside . Anyways here is what I'm thinking is the culprit of the problem. First I was thinking maybe it was just a cat who jumped on it and for some reason triggered the alarm. But on one of the occasions the car was so dirty that there should have been foot prints on top of the car and there was no trace of footprints. No forced entry at all.

BUT what I did notice is this. First off, I love the soft touch closing doors that I NEVER slam my doors anymore. BUT I have noticed that the rear doors seem, "lazy" to close sometimes. On the 2nd time the alarm went off, I did notice my rear left door was still slightly open. So I'm thinking, the car first thinks that all doors are closed when I locked it but then hours later, maybe a slight temp change or whatever, causes a slight tiny movement of the door, and triggers the alarm?

My dealer mentioned to me that they have replaced the mechanism of the soft touch doors on the rear doors of an LS before, but not for the false alarm reason. So far they claim that the customer never complained about the rear doors not shutting all the time.

Do you think the problem is coming from the doors not shutting all the way even though the car should never have locked in the first place when a door is still ajar? Thanks

[Jeff in TX]

I've been thinking about your post for several days. I think you have a dual problem. The intermittent "lazy door closers" seem to not be exceedingly rare. I've had that problem with mine occasionally but not recently and it is always the rear door. When I try to duplicate it I can't and I still think it might be related to logic but since the lock operation always catches it I am not too troubled by it.

What is probably happening with your car is the "lazy closer" syndrome combined with a defective door sensor switch. Many of the cars have experienced problems with the door sensor switches that manifested in a dead battery. This was not well understood until recently when someone posted some good videos. A good explanation can be found in the discussion here: http://www.clublexus...t-wont-set.html

In your case I think what is happening is your door is not closed when you lock your car but it is not detected because the door sensor switch is stuck. Some time later the stuck switch becomes un-stuck, triggering the alarm.

You should replace all four of the door sensor switches. You may be able to live with the lazy closer. Having a stuck door sensor switch on a rear door will not cause the headlight related battery discharge as long as the doors can be locked with the button on the door handle or with the remote wireless key.

[Jeff in TX]

After some more thought, I think the "lazy closer" syndrome may be a direct indication of a defective door sensor switch and that problem may be cured when you replace the switch. It may be that the door closer feature will not work for a door that thinks it is closed.

[Jeff in TX]

I just went out to check to see if the stuck switch would stop the door closer from working and I found that it would still work fine even when the switch is stuck closed.

[denslexusgx470]

I've consulted with my service advisor and he doesn't think so... But so far I've been making sure the doors are shut all the way and so far no false alarms lately

[Jeff in TX]

I think you can demonstrate to yourself that the door-jamb switch is causing the spontaneous alarm that your were experiencing. One way to do that would be to observe the courtesy light on the door to see if it comes on each time you open the door. Try running a test by opening the door 50 times and each time the door is opened observe that the courtesy light illuminates. If the courtesy light fails to illuminate then tap the door-jamb switch with your finger to see if the light will come on.

After some more research I have concluded that the cause of this is not the switch itself, so don't change the switch. Changing the switch would likely fix the problem but would be an unnecessary expense.

[denslexusgx470]

Well I actually have two different problems, after looking back to this thread. I still am experiencing the lazy door syndrome, but I also noticed that the door jamb sensor switch may be faulty too. How I noticed is because when I open the driver's door and press the memory seat, none of the lights turn on and the memory seat doesn't function... until a few seconds later the cabin lights turn on and the seats now react when I press the memory seat at this point.

Both of my rear doors have the lazy door syndrome, and right now it's hard to show the dealer my door jamb sensor issue because it only happens intermittently.

[ZamilAlsharif]

Hi,

Thank you very much for sharing this problem.

My neighbor had this same problem today, yes after 9 years 😅

 

Did you find a solution to this problem?

 

[Cumbiyaa]

I got the same problem.  The SUV alarm went off by itself.  It never happens before when I put my GX460 in the garage.  Recently, I have to work on my house and put the car outside and then it just happens.  Not sure why.