Alarm Keeps Sounding When Locked

[LEDMaestro101]

Good evening all, my first post (but not my first visit) to this fine forum.

I have recently bought myself an '03 IS200 Sport and am loving it....however, after a couple of weeks of no faults, Saturday the alarm started sounding about 15 seconds after I lock the car with the key fob and has done it since. I searched around on the forum and found that this could be caused by a number of things, one of which is due to low Battery voltage.

This leads me to speculate that my Battery is slightly discharged. long story short, I've put footwell lights in and have been doing other minor modifications to the interior and have been leaving my door open for several hours at a time , I really should know better! Also, this morning I noticed my alternator fuse had been blown by the previous and they had bodge it back together with a picture hook! I replaced the fuse today after my internal electrics went dead but everything on the constant 12V feed was working. Everything is back to usual and I assumed that the Battery would charge back up to its previous level on my way home from work, about a half hour drive. When I got home I reluctantly locked the car with the fob and about a minute later the alarm went off.

I have also read that there could be a fault with the internal motion sensor in the dome light but, as I said, the alarm only started going off on Saturday and hadn't given me any trouble which leads me to my first theory.

Basically, is there anything else that could be causing my alarm to go off when I lock the car? I checked the voltage and current draw on the (new) Battery and it's all normal so could it just need a quick top up of juice?

Sorry for the length of this novel! Any help or insight into this would be greatly appreciated :)

Thanks

J

[scudney]

Hi,try changing the Battery in the key fob if that doesn't work then you might have a dodgy sensor

[LEDMaestro101]

Hi Scudney, thanks for your reply. I replaced the Battery in the fob last week (old one was knackered). I've just disconnected the sensor and hey presto the alarm is sound as a pound. There is a small amount of corrosion around the tracks from the sensor connector. I will clean them up with some PTFE spray after work and see if that solves the problem when I plug it back in.

Thanks again

J

[Ncc73]

On 06/07/2015 at 11:55 PM, LEDMaestro101 said:

Good evening all, my first post (but not my first visit) to this fine forum.

I have recently bought myself an '03 IS200 Sport and am loving it....however, after a couple of weeks of no faults, Saturday the alarm started sounding about 15 seconds after I lock the car with the key fob and has done it since. I searched around on the forum and found that this could be caused by a number of things, one of which is due to low battery voltage.

This leads me to speculate that my battery is slightly discharged. long story short, I've put footwell lights in and have been doing other minor modifications to the interior and have been leaving my door open for several hours at a time , I really should know better! Also, this morning I noticed my alternator fuse had been blown by the previous and they had bodge it back together with a picture hook! I replaced the fuse today after my internal electrics went dead but everything on the constant 12V feed was working. Everything is back to usual and I assumed that the battery would charge back up to its previous level on my way home from work, about a half hour drive. When I got home I reluctantly locked the car with the fob and about a minute later the alarm went off.

I have also read that there could be a fault with the internal motion sensor in the dome light but, as I said, the alarm only started going off on Saturday and hadn't given me any trouble which leads me to my first theory.

Basically, is there anything else that could be causing my alarm to go off when I lock the car? I checked the voltage and current draw on the (new) battery and it's all normal so could it just need a quick top up of juice?

Sorry for the length of this novel! Any help or insight into this would be greatly appreciated :)

Thanks

J

Same thing has happened to me. 05 model and after an hour long drive the alarm went off after being parked and locked for 10 minutes.  Fob Battery OK,  car Battery charge OK, so I'm going to have a look at the sensor in the light for corrosion. I presume disconnecting it is relatively straight forward?

As a new owner and member of the club these feeds have been very useful.

Thanks

N

[TigerFish]

Sometimes if you have loose change on/in the centre console it can trigger false alarms.

Sent from my Iphone using Lexus OC

[LEDMaestro101]

Disconnecting is as simple as unplugging the connector in the sensor unit. I replaced mine with a known working unit and still the problem persisted so I just put the original back in and left it unplugged. 

J

[LEDMaestro101]

Mine did have a small amount of corrosion but even after cleaning with PTFE and tidying up the metal tracks, it still gave me problems so, as I said, just left it unplugged.