[schodk]

Hi

I hope this is the right place to post this - I am looking for advice on my Mazda 3 (2010) TS3 diesel.

For a while now the alarm has been going off on its own, at random times day or night, and I can't see an obvious pattern or cause.

The battery is relatively new, replaced 8 months ago. Although the car was sitting without use for a good couple of months (lockdown) it has then had a couple of good runs since then including 150 mile round trip 2 weeks ago and maybe 5-10 short runs (10 mins or so) per week over the last 2-3 weeks. I'm assuming it's not a low battery for that reason - someone has put a volt reader on it and it doesn't show as being low.

I've tried turning off the internal alarm sensor thing on the remote key fob and it still goes off.

I've tried WD40 and cleaning up the boot latch, and it still goes off.

Is there anything else I can try? Any other possible cause?

It went off at 3am last night and it's in a residential street so this is causing me a lot of concern! I can't get to a Mazda dealer either at the moment and not sure this is something a local garage could help with (perhaps specialist?)

Any ideas and tips would be very much welcome!

thanks,
Dan

 

[Mike C]

I had a 323 that started sounding its horn randomly typically early in the morning- that turned out to be the insulator sheet in the horn pad contracting when it got cold then allowing the copper conducting surfaces in the horn to contact. When I dug around this was a common problem with 323's. I also had a GMH vehicle that sounded its alarm any time of day- that was caused by a dry joint in the security module it went away when I touched every joint in the module with a hot fine tipped soldering iron .

 

[schodk]

I had a 323 that started sounding its horn randomly typically early in the morning- that turned out to be the insulator sheet in the horn pad contracting when it got cold then allowing the copper conducting surfaces in the horn to contact. When I dug around this was a common problem with 323's. I also had a GMH vehicle that sounded its alarm any time of day- that was caused by a dry joint in the security module it went away when I touched every joint in the module with a hot fine tipped soldering iron .

Hi Mike

Thanks for the reply! The issue I'm having is with built-in theft deterrent alarm rather than the horn - the noise that goes off is very much a 'siren alarm' rather than a horn honking, if that makes sense!

Not sure what you mean by GMH or security module though - sorry - just an average driver with no tech skills when it comes to cars.. is that something easily checkable by local garages?

thanks!
Dan

 

[Mike C]

Intermittent electrical faults are difficult and generally costly to fix , due to the time wasted in getting the fault to recur. A dry joint is a soldered joint, on say a PCB, that makes intermittent contact. This often occurs when the component is cold and the metal in the joint contracts.
If I suspect a dry joint is causing a problem I have to identify the component that caused the problem, then remove the component and inspect/resolder every suspect soldered joint in the component. Note : a code check may identify the suspect component but to be really sure you need to check the body control computers, not just the engine systems.
If you have a local auto-electrician he could do it, but unfortunately auto-electricians are a dying breed in many areas.

 

[schodk]

Intermittent electrical faults are difficult and generally costly to fix , due to the time wasted in getting the fault to recur. A dry joint is a soldered joint, on say a PCB, that makes intermittent contact. This often occurs when the component is cold and the metal in the joint contracts.
If I suspect a dry joint is causing a problem I have to identify the component that caused the problem, then remove the component and inspect/resolder every suspect soldered joint in the component. Note : a code check may identify the suspect component but to be really sure you need to check the body control computers, not just the engine systems.
If you have a local auto-electrician he could do it, but unfortunately auto-electricians are a dying breed in many areas.

Hi Mike - thanks for the advice. I checked ECU codes and nothing registered - will try calling some garages today I think as it went off again 7am this morning...

Dan

 

[Mike C]

Hi Mike - thanks for the advice. I checked ECU codes and nothing registered - will try calling some garages today I think as it went off again 7am this morning...

Dan

I know it can be very embarrassing - neighbour's notes under your wiper blades etc. Hope you can find a garage that will tackle it.

 

[dexnic]

Hello Dan, I just found your post while searching as I am currently having the same issue, alarm on my mazda 3 has started randomly going off once a day. Did you manage to resolve it and what was it if so? Many thanks

 

[Taylor.b]

Hello Dan, I just found your post while searching as I am currently having the same issue, alarm on my mazda 3 has started randomly going off once a day. Did you manage to resolve it and what was it if so? Many thanks

Sounds like one of your door actuators, if your car beeps when you lock it then your actuator is locking but is shorting / wires are probably touching, so your anti theft system is registering your car is unlocked. I would see if you haven’t gotten it fixed if you have a faulty actuator