L322 Range Rover alarming at random

Hi All,
I’m new to this forum so firstly apologies if this query has been posted 1000x before and apologies it’s a bit of a long post.
I’ve got an 2011 L322 which approx 4 months ago set the alarm off around 30 minutes after it had been driven late at night. Unlocked and relocked and no further alarm. Same thing a couple of weeks later, reset after locking. All okay until about 2 months later where the alarm sounded but a couple of minutes later went off again, only way to stop it repeatedly going off was to leave the car unlocked. Recently been getting progressively worse to the point it’s now going off a couple of hours after using the car pretty much every time it’s used and sometimes it isn’t stopping when the car is unlocked. Even got to the point a couple of days ago where it was alarming on and off repeatedly as I tried to drive it away but it did stop after a minute or two. Tried the trick of removing the wiring from the bonnet switch earlier today and did seem to last longer but about 4 hours after parking it went off again. Even tried leaving the car on a trickle charger for the battery for a few hours today to rule out the battery being flat but it hasn’t made a difference. Any help or suggestions would be very much appreciated!

The internal volumetric sensor is also a known cause of random alarm activations as well as the bonnet switch (which you already mention!)

If you can/tried to drive it while the alarm is going off.
A few hrs on trickle will do nothing for the battery. first place to start, have you history of battery?
I will be watching this.
Good luck.

J

Thanks for your replies guys.
I’m leaning more towards it being a potential battery issue but it was replaced by a previous owner back in 2016. I did have an issue where it went completely flat last winter as it was left standing for a couple of weeks and temperatures had dropped below -10C most nights over this period and trying to cold start it drained it pretty much straight away. I managed to jump start it (with a lot of effort) so I’m wondering if this has had a knock on effect now.
I don’t get much opportunities to drive for semi-long distances (maybe only 20+ miles trips once a week) and majority are short trips in between so no real chance of giving the battery a ‘good charge’. Booked in at a local Land Rover specialist 2 weeks today (no surprise they’re busy!) and it’s currently parked in my parents garage unlocked to stop the alarm going off. Hopefully once it’s looked at it’ll be sorted quickly (and hopefully quite cheaply but being a Range Rover I’m not holding out much hope….)

Start with a good known (new) battery. Then move on from there

J

If the battery was new in 2016 thats five years and went completely flat last winter, i would say the battery is toast, you dont need to have a garage check it and change it, just buy a new one the biggest that will fit mf31 120ah 1000cca i believe, it only just goes in by mm`s, you have to put the bonnet in service mode to get it in
the dealers will charge you more to test it than the battery will cost.

brianp38dse said:

just buy a new one the biggest that will fit mf31 120ah 1000cca i believe, it only just goes in by mm`s

Click to expand...

Not sure of the size but I know I skinned my knuckles putting the big Bosch in and had to reconfigure the mega fuse (Lhd).
So not sure the mf31 will fit with the center posts.

J

marjon said:

Not sure of the size but I know I skinned my knuckles putting the big Bosch in and had to reconfigure the mega fuse (Lhd).
So not sure the mf31 will fit with the center posts.

J

Click to expand...

Others will know more than me, but the biggest that will fit is the way to go

brianp38dse said:

Others will know more than me, but the biggest that will fit is the way to go

Click to expand...

Can’t agree more bigger is bestest .

J

Fits in my 05 TD6 with more than a few mm spare

Check bonnet switch. If I remember correctly, you can disconnect it & car thinks bonnet is closed.

Fitted à numax or Hankook equivalent. Unfortunately there isn't a heal on the battery for the plate to lock it down. I did however fit a strap and buckle type ribbon. Sorted