Mazda 6 Car Alarm keeps going off! Help! :)

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My father in law had a 2009 Mazda 6 and that started having the alarm go off at random times, usually in the night, with in a week or two the car battery died. Pretty sure it did this twice. Anyway, he replaced the car battery and after that it was fine.
 
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My father in law had a 2009 Mazda 6 and that started having the alarm go off at random times, usually in the night, with in a week or two the car battery died. Pretty sure it did this twice. Anyway, he replaced the car battery and after that it was fine.
I know mine could do with a new battery, the current battery is the smallest capacity recommended for the vehicle.
I intend to get the larger capacity battery, however I am going to leave replacing it (and new tyres) until the vehicle is back in regular use.
 
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I had the same car and very similar problem with the alarm going off in the middle of the night. I done the same things like changing the battery etc and it was driving me nuts. For me i think it was something to do with the remote central locking but i may be wrong. It seemed when i locked the car via the physical key it never went off.
 
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Hello. I've had the same issue on my
2010 Mazda 6. The hot weather has definitely been a cause. It's been to the garage, no fault codes, new battery installed. on the same day I discovered something new to try, I've trawled the internet and found it could be the heat pressurised in the car mixing with cooler air thats Triggering the alarm.Shut all vents, point the direction of vents to the footwell and set the heat high. You can switch the heater off. For the first time in a week forgot to shut all vents and it went off yesterday morning at 8.30am. Someone has mentioned it could also be a separate battery for the alarm? It's very embarrassing if nothing else!
 
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Hi guys, thank you for the additional responses. It really has been helpful. I wanted to give an update.

It actually has been behaving itself for the past few days and I got a garage to look at it for free this morning. They've hooked it up to the diagnostic equipment and it is coming up with the same trigger for the alarm each time, which is the boot locking mechanism. They said a new boot lock mechanism was coming up at £280 + VAT! So, I took the car away again and they're fine with me sourcing one myself. I've seen a few already which i think appear to be the same thing from my age of mazda (2010) for £20-40, and the garage will happily fit it. They said they'd like me to get the microchip too, from the button on the car where you press it to open the boot.

I believe it is against forum rules to link to a well known auction site on here, but I'm enquiring at the moment! :)

And finally, it really has been hot the past few days and I would have expected the alarm to have gone off multiple times... but having followed some advice on this thread and slamming the boot shut quite hard.... I'm wondering if that alone is fixing my issue, so I perhaps could do to wait briefly to see if it even does it again.
 
Soldato
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Hello. I've had the same issue on my
2010 Mazda 6. The hot weather has definitely been a cause. It's been to the garage, no fault codes, new battery installed. on the same day I discovered something new to try, I've trawled the internet and found it could be the heat pressurised in the car mixing with cooler air thats Triggering the alarm.Shut all vents, point the direction of vents to the footwell and set the heat high. You can switch the heater off. For the first time in a week forgot to shut all vents and it went off yesterday morning at 8.30am. Someone has mentioned it could also be a separate battery for the alarm? It's very embarrassing if nothing else!

Hah, interesting! I hope you've found a permanent solution there. It must be especially frustrating with no fault codes coming up.
 
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Oh, I forgot to mention one thing above by the way. Could anybody with an MK2 Mazda 6 (2010 in my case), please do me an enormous favour if they remember at some point. Could somebody please close their boot as they normally would, and as the boot slams shut, do you see the boot itself clearly shift upwards by perhaps a few millimetres or so a fraction of a second later? The garage thought the fact that mine does this was further confirmation of the boot locking mechanism issue. They seemed to think when you slam it shut, there should be no movement upwards at all.
 
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Hi guys, thank you for the additional responses. It really has been helpful. I wanted to give an update.

It actually has been behaving itself for the past few days and I got a garage to look at it for free this morning. They've hooked it up to the diagnostic equipment and it is coming up with the same trigger for the alarm each time, which is the boot locking mechanism. They said a new boot lock mechanism was coming up at £280 + VAT! So, I took the car away again and they're fine with me sourcing one myself. I've seen a few already which i think appear to be the same thing from my age of mazda (2010) for £20-40, and the garage will happily fit it. They said they'd like me to get the microchip too, from the button on the car where you press it to open the boot.

I believe it is against forum rules to link to a well known auction site on here, but I'm enquiring at the moment! :)

And finally, it really has been hot the past few days and I would have expected the alarm to have gone off multiple times... but having followed some advice on this thread and slamming the boot shut quite hard.... I'm wondering if that alone is fixing my issue, so I perhaps could do to wait briefly to see if it even does it again.
I also gave the tailgate hinges and lock a spray with WD-40 to eliminate any friction when closing the boot.
My wife still can't understand why I open the side door every time I close (slam) the boot.
 
Soldato
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I also gave the tailgate hinges and lock a spray with WD-40 to eliminate any friction when closing the boot.
My wife still can't understand why I open the side door every time I close (slam) the boot.

And thanks to you, my partner is also going to be wondering what on earth I'm doing it for! :) but hugely appreciated! Ever since i started doing this, it hasn't actually gone off. Although it did go off after i'd done the WD40, but maybe i didn't slam the boot hard enough.
 
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Oh, I forgot to mention one thing above by the way. Could anybody with an MK2 Mazda 6 (2010 in my case), please do me an enormous favour if they remember at some point. Could somebody please close their boot as they normally would, and as the boot slams shut, do you see the boot itself clearly shift upwards by perhaps a few millimetres or so a fraction of a second later? The garage thought the fact that mine does this was further confirmation of the boot locking mechanism issue. They seemed to think when you slam it shut, there should be no movement upwards at all.
Gone out to mine just now - boot closes as follows:
Slam shut - motor operates and boot goes down (below flush) - slight pause - motor operates and boot raises a few mm (flush).
 
Soldato
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Gone out to mine just now - boot closes as follows:
Slam shut - motor operates and boot goes down (below flush) - slight pause - motor operates and boot raises a few mm (flush).

Oh, thank you very much for that! This is identical to mine currently, so the garage's theory was wrong on this, but it does seem like the lock definitely has an issue if the diagnostic tools are to be believed.
 
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Another common fault is the rubber boot button perishing and water getting in. This can cause the button to go a bit haywire. I’d check that out first before replacing the locking mechanism.
 
Soldato
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Another common fault is the rubber boot button perishing and water getting in. This can cause the button to go a bit haywire. I’d check that out first before replacing the locking mechanism.

It really does seem more prone when it is very hot/sunny. It seems to just not do it when the weather is cold/rainy.

Also, update... just slamming the boot doesn't work! The alarm just went off right now :(
 
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It really does seem more prone when it is very hot/sunny. It seems to just not do it when the weather is cold/rainy.

Also, update... just slamming the boot doesn't work! The alarm just went off right now :(
I use the word "boot" to mean both tailgate and trunk - is your vehicle a saloon (trunk) or hatchback (tailgate) ?
 
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They've hooked it up to the diagnostic equipment and it is coming up with the same trigger for the alarm each time, which is the boot locking mechanism

There you go ;) sometimes it's easier to just pay a bit of money to have it looked at than to mess about for weeks. It's obviously worth trying the simple things first but a diagnostic can save a lot of time!

On some vehicles, it can be a common fault for the external boot release button to get water in it and cause alarm issues. Although it may well be down to the microswitch inside of the boot latch breaking contract occasionally causing the alarm.
 
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Mine is the hatchback version.
There is a "Liftgate Latch Position Switch" positioned somewhere near/on the boot lock.
It has four switches within it.
All four switches are connected to the "Liftgate Auto Closure Control Module"
One of those switches also feeds both the "BCM" and the "Cargo Compartment Light"
BCM then feeds the "Theft-Deterrent System".

  • Something you could try:
    • Remove the rear parcel shelf.
    • Verify that the boot light is on.
    • Shut the tailgate gently.
    • Verify that the boot light goes out.
    • Bounce the vehicle / push down on the tailgate - does the boot light come on / flicker?
  • Try the above again, this time closing the tailgate with a slam - same result?
 
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