Author Topic: Horn honks when boot lid or bonnet is opened Mazda 6 1.8L 2007  (Read 2188 times)

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Offline kp1983

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  • Engine: 1.8L
  • Fuel: Petrol
  • Transmission: Manual
  • Trim: TS
  • Year: 2007
Horn honks when boot lid or bonnet is opened Mazda 6 1.8L 2007
« on: February 09, 2016, 12:28:53 pm »
Hello Everyone,

I am a new member and looking for some help from the members on this forum.

I bought a used 2007 Mazda 6 1.8L TS in January 2016. My car has very unique problem.

When I open the boot lid or the bonnet the car makes really loud single horn beep sound,, which is really annoying/embarrassing when you are in a public area like mall parking or resident parking. This issue is not consistent, the car horn will not beep for about 2-3 days though I open the lid or boot, but the it will reoccur after 2-3 days and will continue for about 4-5 days and again will repeat the similar cycle.

I tried to unlock the car with spare remote, replaced the remote batteries, disconnected car battery for about 10 minutes but nothing worked.

I tried disconnecting the lock/door (lid) ajar sensors and following are the results.

1.bonnet sensor connected & boot lid sensor connected- horn will beep on opening boot or bonnet (but this is not consistent), indicators will flash upon locking the car.
2. bonnet sensor disconnected & boot lid sensor disconnected - no horn beeping when boot or bonnet is opened but indicators will not flash when i press the lock button on remote but car is locked
3. bonnet sensor connected & boot lid sensor disconnected -  everything works fine, horn will not beep if i open boot lid or bonnet and the indicators will also flash upon locking the car.

Someone please HELP!

(Please ignore any grammer or spelling mistakes)

Thanks,
KP

Offline steve46

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Re: Horn honks when boot lid or bonnet is opened Mazda 6 1.8L 2007
« Reply #1 on: January 13, 2021, 10:40:21 am »
I have this exact same issue, did you ever find out what the cause of this was?

Or does anyone else have any ideas? I've changed the car battery, but it has not helped.

I have also found that when running an OBD scan the cars horn honks several times whilst the scanner is connecting /reading codes - three long honks and then a very short one.

Thanks for any help!

Offline steve46

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  • Year: 2011
Re: Horn honks when boot lid or bonnet is opened Mazda 6 1.8L 2007
« Reply #2 on: January 17, 2021, 10:23:15 pm »
Just in case anyone else is looking for a solution to this or a similar issue:

A few months ago I had the windscreen replaced, the first attempt at this was done poorly and water leaked into the car.

I've read elsewhere that the 2001-2007 Mazda 6 is prone to having water damage to the BCM which can lead to all sorts of issues with the alarm/locking system.

So this evening I opened up the BCM and found that there was corrosion on a few of the terminals on the circuit board.
I cleaned the board with contact cleaner to remove the corrosion between the terminals and my issue has completely resolved!

If this hadn't worked my next step would have been to replace the BCM with a 2nd hand one from a well known online auction site.

Offline Elwood

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  • Colour: Velocity Red (27A) Metallic
  • Engine: 2.0L
  • Fuel: Diesel
  • Transmission: Manual
  • Trim: TS
  • Year: 2007
Re: Horn honks when boot lid or bonnet is opened Mazda 6 1.8L 2007
« Reply #3 on: January 18, 2021, 08:25:41 pm »
Great! But what's the BCM for the uninitiated?

Offline apav

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Re: Horn honks when boot lid or bonnet is opened Mazda 6 1.8L 2007
« Reply #4 on: January 19, 2021, 06:17:24 am »
That is the body control module. It is next to the internal fuse box.

You will need to remove a bit of plastic to reach it for removal but you may be able to disconnect it for terminal cleaning.