Alarm Going OFF?

[Nigel Coleman]

So the last few days the alarm goes off by itself for a short period then stops. It's happened 4 times and I'm now getting funny looks from the neighbours!

I checked that the boot, bonnet, doors and windows are properly closed - and they all are.

Any ideas please?

[Malc1]

something metal in the centre console arm rest maybe .......  this sometimes affects the Ls400 alarm

Malc

[DavidCM]

Spider/fly lurking inside and triggering the alarm?

[Nigel Coleman]

Bad Battery? 

Don't know when it was last changed

[Glyn Jennings]

I have same problem with windy or thunder and lighting conditions which sets off the tilt sensor as my car has a car cover on it. You can disable this function it is in the manual. From memory you have to open the door and open & close the door lock several times within a short time and the security light will flash for a period of time. I know it is in the manual but I can’t remember the exact procedure.

[Tomtit]

My LS430 sometimes does this. I just put the Battery on charge to top it up and the problem goes away.

[Localhero]

As Glyn says, when leaving car press on off door lock button 3 times alarm light will flash rapidly then close door and lock with remote, this turns microwave sensor off so you can leave pets or mother in law locked in car😄

[Nigel Coleman]

Do you need to do this every time or is it a reset?

[Localhero]

No it's not a reset it just stops the sensors that pick up movement in the car but if you have an insect etc trapped in your car the sensors won't pick it up, I have also noticed if I leave my phone in the car that that can set the alarm off too, hope this helps👍

[Localhero]

On 04/05/2023 at 3:32 PM, Nigel Coleman said:

Do you need to do this every time or is it a reset?

This reminds me of the blonde who took her Mini into a garage technician said nothing to worry about! Just crap in the air filter, blonde said how often do I need too do that!!!! 😃I'll get my  coat 

[Thackeray]

On 4/27/2023 at 5:32 PM, Nigel Coleman said:

So the last few days the alarm goes off by itself for a short period then stops. It's happened 4 times and I'm now getting funny looks from the neighbours!

I checked that the boot, bonnet, doors and windows are properly closed - and they all are.

Any ideas please?

In earlier threads about alarms going off, the culprit is often an insect trapped in the car. As Spring arrives, there are probably more insects around unexpectedly triggering car alarms.

[Nigel Coleman]

Don't think it was the Battery as it only needed a hour and a half trickle charge to get to full charge.

[Nigel Coleman]

Have resorted to leaning across and locking the passenger door from inside then locking the car (drivers door) with the key - this disables the alarm (as per handbook instructions).

Not ideal but the neighbours are happy.

I'm having problems with local garages not even wanting to look at the car to fix it.

Also still having problems with the rear parking sensors - and just discovered what appears to be a front parking camera installed?

I love my car the drive and mechanics are great but these electrical problems are annoying and let it down.  😒

[Neil E]

It seems you have a little gremlin in there somewhere. It may not be his handywork but RW did sometimes fit front cameras so that's quite likely. Does it have a rear camera that displays on the sat nav screen?  

 

[Nigel Coleman]

No, just faulty rear parking sensors which buzz for 4 seconds when reverse is selected then don't work.

[KeithMano]

On 5/4/2023 at 10:12 PM, Localhero said:

No it's not a reset it just stops the sensors that pick up movement in the car but if you have an insect etc trapped in your car the sensors won't pick it up, I have also noticed if I leave my phone in the car that that can set the alarm off too, hope this helps👍

I was going to open a thread on this topic, but thought I should search first.

Was in a quiet country village in the week and the alarm went off. Despite me stopping it with the remote it kept doing it again and again. Very embarrassing. Read the manual in the glove box and tried the locking and unlocking x3 thing, but it didn't help. Then I realised I'd left my phone inside the central storage bit. Once I took it out, the alarms finally stopped. 

I'm guessing the phone was somehow interfering with the electrics and triggering it. Glad to find some confirmation with your reply! 

[Nigel Coleman]

Keith. While recently recolouring my leather seats I found the location of the alarm sensor. It is very easy to get at being directly under the heated seats switches. The trim is easy to remove, start at the back area near the armrest lock. 

Yes a mobile phone would be extremely close to this sensor when inside the central storage under the armrest - I don't know if this actually causes any problems though?

I have purchased a tested replacement sensor from a breakers on eBay for £20.00. It is from a SC430 which did only 39,000 miles while mine has done well over 100,000 miles.

However this sensor may not be the cause of the alarm fault as there is at least one other alarm sensor/ECU on the car - but I have no idea of it's location?

I'll fit the sensor tomorrow and report back.

 

 

 

[Malc1]

2 hours ago, Nigel Coleman said:

I'll fit the sensor tomorrow and report back.

I know in my Mk3 Ls400 the solution was to

a) keep metallic bits and bobs out of the centre armrest console and 

b) to turn the alarm button to zero/ right down when you get to it underneath the centre console as mentioned with access afore 

There was no need for me to buy a new sensor ......  just to wind it down !

Malc

[Nigel Coleman]

Hi Malcolm,

With the SC430 so far I have only found the one sensor under the heated seats switch and that one is not adjustable. As I said before there is at least another sensor somewhere or maybe even 2 which may also be the fault cause?

[Nigel Coleman]

Photo of alarm security sensor (with part number showing) located directly under the heated seats switch. You might have to put the gear shifter in Neutral and remove the wood trim to unplug the cable:-

[Nigel Coleman]

Have not heard it go off when parked for the last 2 days and no phone calls from the neighbours (asked them to ring me) so looks like it's a fix?

I don't know if you can get these sensors new from Toyota/Lexus but got mine tested and used from eBay. Try and get one from the lowest mileage car that you can. Mine has done over 80,000 miles less than the original one in my car so in theory it's had less use.

Also in location the sensor just sits loose on a metal cradle with some foam padding so I have added some extra foam to prevent movement when going over bumps.

[Nigel Coleman]

The Alarm is still working properly after replacing the sensor.  

[Nigel Coleman]

Did leave my mobile phone in the drivers door pocket yesterday lunch time for the first time since replacing the faulty sensor.

Yes 3 hours later the alarm went off. Removed the phone and back to normal again.

You are right Malcolm, stupid mobile phones will set off the alarm on a working sensor (before with my faulty sensor the alarm was going off all the time even without a mobile in the car)

Must be phone message notification vibration or ringing setting it off?

[Nigel Coleman]

Replacement sensor still working correctly.

Still remembering NOT to leave the mobile phone in the car.