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

bobert50

bobert50

bobert50

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Hi guys,

I've been trying to get to the bottom of my car alarm problems for the past month and any help would be very appreciated. Here is roughly what has happened so far....

In Early May, the car alarm on my 2010 Mazda 6 started going off throughout the day. My immediate thought was batteries... I changed both of the batteries in my key fobs and then waited to see if this fixed the problem.

The next day, still the alarm is going off... I 'm starting to see a bit of a pattern with hot weather/sunshine but that was just a theory. I decided that since i knew the car battery was very old that this should be the next thing to replace, so I picked one up and did that myself, gave it a good run-around so the ECU-re-learnt everything and then left it parked at my house again. Basically, during the coronavirus, my car really isn't getting much use! There also seems to be a possibly related issue where my boot occasionally seems to be unlock itself and opening slightly (not fully up). This has happened about 5 times in this same period that the alarm is going off and never happened before this.

Anyway, it stayed quiet for a day or two and then off the alarm goes again! I was on the verge of taking the car to a proper garage to see if they could find any info on perhaps a dodgy sensor, and then a few weeks ago... the sun vanished, and the alarm didn't go off for weeks at all. I'm certain that the alarm stopping seemed to completely 100% coincide, to the day, with a drop in temperature, and was worried when the temps increased again lately, but the alarm continued to stay off... until last night!

My neighbour rang my bell this morning to say that my alarm was going nuts at 5am this morning :( I somehow didn't actually hear it myself but I'm sure he'll be telling the truth. He said it went of three or four times all close together and stopped within about 5 seconds, which is totally in-keeping with the previous behaviour. It hasn't gone off since but it does seem inevitable that it will.

If i had to guess... i have serious suspicions that, with the timing of this recent one happening, and the fact i happened to use the car the previous day (for the first time in weeks), and i did open up the boot, and the fact that there is possibly a related issue with the actual boot, it possibly could be the boot sensor?

Has anybody got any ideas what I could try before taking it to a garage on Monday? I'm not even sure what the sensors look like or if i could wipe along them myself, or whatever else is an option to me. I feel pretty guilty / bad for my neighbours right now and really would like this sorting asap! preferably without costing myself an absolute fortune.

Any thoughts are extremely welcome! :)
 
Last edited:
Meaker said:
Is it following a pattern with the rain we have had? Maybe a leak?
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Hmm, it doesn't seem to. It seems more likely warmer temps/blazing sunshine that triggers an increase of the alarm going off. I've tried to see if it is damp anywhere and everywhere seems completely dry. I feel 75% sure that going into the boot of the car recently for my tyre pump is what probably led to it going off again during the night last night, since it hadn't gone off for two or three weeks and it had rained a lot in this period.
 
DereksDontRun said:
have you left/got anything electronic in the car? phone, tablet, etc?

I know it sounds dumb, but I used to have a Mazda 6 MPS, which I know is a little older than this, but they're renowned for the alarm to go off randomly if there's a phone or tablet left in the car, even if it's in the glovebox or tucked away in the seat pockets.
Click to expand...

Thanks for the reply. Unfortunately absolutely nothing is in the car :(
 
IAmATeaf said:
Said that he has.

Take a look at all the door, bonnet and boot sensors and check if you can to see if they look clean etc.
Click to expand...

Thanks for the help. This'll sound a really stupid question, but i can see for example the boot locking mechanism but I'm not even sure what part / where the sensors are! A bit embarrassing! :) I did use some wd40 on the lock earlier today to see if that helps on the major locks.

Right now, I'm just REALLY hoping it doesn't go off at 5am again and disturb the neighbours.
 
Paul_RD said:
I've got a 2008 Mazda 6, and it has a tendency to do funny things if it doesn't detect all the doors and boot are shut properly (even though they are).
I make sure I regularly lubricate all door locks and hinges so the doors shut easily.
To ensure my tailgate is shut properly, I open one of the doors so the air pressure doesn't build up and this means i can give the tailgate a good slam down.
I also make sure I close my doors with a good slam as well.
It sounds brutal but it seems to work.
Click to expand...

Thank you! I'm going to do exactly this during the afteroon. No alarm of late and long may that continue!
 
Paul_RD said:
Thanks Silent Bob, that reminds me - when you lock it bobert50, press the button on the remote twice, if the hazards flash once, then flash three times after a few seconds, the vehicle is happy.
If you don't get the three flashes, something is wrong - open and slam shut all the doors (including the bonnet and tailgate) and try again (or use the key).
Click to expand...

Hi, I'm really sorry for the late reply! Thank you very much everyone for the thoughts and replies.

This thing about the three flashes I will try in the morning 100%. I'll be very very curious!
 
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.
 
Sophie Hamilton said:
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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Hah, interesting! I hope you've found a permanent solution there. It must be especially frustrating with no fault codes coming up.
 
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.
 
Paul_RD said:
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.
Click to expand...

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.
 
Paul_RD said:
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).
Click to expand...

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.
 
Silent Bob said:
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.
Click to expand...

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 :(
 
Paul_RD said:
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?
Click to expand...

Thank you so much for the help. I'm going to have a mess before it goes dark :)
 
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