Electronics glitch or sensor issues?

[62yg]

Hi so I have a 2011 Jazz I-Vtec Es. I hope this is the right thread. I get an intermittent problem where the alarm will go off after leaving it. It can be from a few hours to a whole day.

When I go to turn the alarm off both the key remote's lock buttons stop working but unlock button still works. The lock button on the driver's door still worked fine too and manually locking was also fine. I tried slamming all doors including the boot multiple times which didn't have any effect. I tried pairing the keys to the car again and that didn't help, only the unlock button worked still. I also replaced the battery of one of the keys.

I then noticed the alarm light wasn't lighting up on the dashboard so I reset the alarm and it flashed for a minute and then the alarm sounded (not sure if that's supposed to happen? when you reset it?) The red dashboard alarm light was blinking again after I re-locked it but the keys still didn't work.

I left it about an hour and came back and suddenly the lock button was working fine again.

It's happened twice in two years so far.

Not sure what to do so any advice would be greatly appreciated if anyone had something similar?

Thanks.

[VicW]

I can't help with your problem but I have a 2011 Jazz EX and it doesn't have an alarm only an immobiliser. None of my previous Jazz's had alarms either.

Vic.

[culzean]

You may have a dodgy door switch,  because doors will not lock if the system thinks a door is open,  and if it thinks a door is open after alarm is set the alarm will sound.  The other thing is battery voltage, alarms are notorious for draining the car battery with their high parasitic drain,  and if the alarm senses low battery voltage it may well think someone is tampering and set the alarm off.   If your battery is 5 years or more old or you are not sure how old it is ( if it is original it will be 9 years old now ).  Check battery terminal voltage ( leave it at least an hour after driving or charging ) normally a decent battery in good shape should be 12.6 volts, if it is below 12.2 volts volts a few hours after charging you need a new one.

https://www.tayna.co.uk/car-batteries/yuasa/ybx5054/