My 2003 TL Magna has had it's alarm go off about once or twice a day randomly for the past week and I'm unsure why. It's parked in the garage and no-one is touching or any animals running into it.

Is there any way to reset the alarm system or something?

Disconnect the negative battery terminal and pump the brakes? I know thats a method for draining the electronics, but whether or not it will make the problem worse or not, I don't know.

Would be checking the door switches to see if ones abit sticky
Also check the boot and bonnet ones

Bonnet one is the one that gives the most trouble. Easy to check, just lock the car and wriggle the bonnet on the driver's side. If the alarm goes off there is your problem!

Fix can be:

(a) Tighten the bonnet catch so the bonnet sits a bit lower.
(b) Shim up the bonnet switch.
(c) Ghetto fix - glue a small coin where the switch touches the under side of the bonnet.

Also check your alternator charging volts and battery as low voltage in battery can also cause this

Barry

had to adjust bonnet catch on mine once or twice after bonnet was used as seat by 3 ppl.........big ppl

Thanks for the tips guys - will run through the car and see if there's anything closed not quite right. Battery could be an issue too (it's about 5 years old now)

Yeah the bonnet switch is almost guaranteed to be the culprit. What my mechanic did is space it up with a washer underneath it for a cheap fix. It runs along the front "radiator support" bar just behind the radiator, if you hunt around you'll find a little switch you can push up/down like a door switch. its probably black.

I had this exact same problem in my TL.

Also I found I couldn't reliably "test" the bonnet switch, it must take a while to arm or something. Despite the fact my alarm could reliably go off 3 times in 1 night :P