horn going off when lock car

[mate]

hey guys

is my horn supposed to go beep when i lock the car after having the bonnet open?

or is there something wrong with my alarm?

[Ferret]

Alarm beeps because bonnet is not shut properly, or a least the limit switch which tells the alarm the bonnet is closed is faulty.

[mate]

Alarm beeps because bonnet is not shut properly, or a least the limit switch which tells the alarm the bonnet is closed is faulty.


oh ok so if the switch is faulty how is it knowing the bonnet was opened in the first place?

[Pedro_The_Swift]

also beeps when a door is open:D

[AndrewMilne]

hey guys

is my horn supposed to go beep when i lock the car after having the bonnet open?

or is there something wrong with my alarm?
Mate,
The same happens with my D2a, if I lock the car using the remote key fairly soon after closing the bonnet (or if any door is not properly closed).
However, it seems to me that if you wait longer (don't know how long, but say, 15 minutes or more after closing the bonnet) before locking, the alarm does not sound a beep.
Try it and see what happens for you.
Cheers,
Andrew

[rar110]

My L322 does that due faulty bonnet switch bracket. I pulled the plug on the switch. I found the bracket holding the switch had some wear allowing the switch to move a little.

[AndrewMilne]

My L322 does that due faulty bonnet switch bracket. I pulled the plug on the switch. I found the bracket holding the switch had some wear allowing the switch to move a little.

Hi rar110,
Did you manage to make any modification to the switch bracket, such that the alarm now does not sound when you close the bonnet and then lock up?
Cheers, AndrewMilne

[DiscoDB]

Mate,
The same happens with my D2a, if I lock the car using the remote key fairly soon after closing the bonnet (or if any door is not properly closed).
However, it seems to me that if you wait longer (don't know how long, but say, 15 minutes or more after closing the bonnet) before locking, the alarm does not sound a beep.
Try it and see what happens for you.
Cheers,
Andrew

After you close the bonnet, open and close a door and you may also find the horn then does not beep when you lock the doors.

[AndrewMilne]

After you close the bonnet, open and close a door and you may also find the horn then does not beep when you lock the doors.
DiscoDB: I'LL definitely try that idea!


Andrew

[rar110]

Hi rar110, Did you manage to make any modification to the switch bracket, such that the alarm now does not sound when you close the bonnet and then lock up? Cheers, AndrewMilne

Not yet. The plan is to cut some thin alloy sheet the same shape as the top of the bracket and sicaflex that to the bracket. The model after mine has a steel bracket so it must have been identified as a weakness.

[DiscoKym]

Mine beeps the horn after closing bonnet all the time.

Now after closing bonnet I press remote open and then close.

No horn blowing... :)

[lewy]

I think if the horn sounds it hasn't armed the alarm

[sierrafery]

I have a theory on this but can't vouch is 100% perfect but i couldnt find other explanation, the fact is that the bonnet switch's input has a different pattern than the door switches and dedicated input in the BCU, the door switch inputs are directly recognised by the BCU cos it's about open circuit or closed to earth input:



The input from the door latch switches to the BCU is either zero volts or an open circuit. Zero volts indicates the door
is open. An open circuit indicates that the door is closed. When the BCU sees an open circuit, it pulls the input high internally

now, the gist is here IMO:



When the bonnet is closed the bonnet activated alarm switch is in an open condition and the input to the BCU is more
than 6 volts, in which case the BCU pulls the input high internally. When the bonnet is open the bonnet activated alarm
switch is closed and the input to the BCU is less than 2 volts.
i couldn't find the BCU's internal electronic diagram to see what kind of voltage monitoring setup is there to identify the difference between "less than 2" and "more than 6" volts but there are cases when such circuit could have a delay untill the main component is ''triggered" cos the voltage must rise within by missing the earth path and in this case if the BCU gets a lock command before that "more than 6V" signal was recognised it will interpret it as misslock at the bonnet and give the warning

i made tests on mine cos i was curious and i found out that this delay can vary between 30 and 90 seconds also an ignition on or unlock command from the fob would reset this thing that's why then there's no misslock sound

my final onclusion is to not bother too much with it as long as it happens only in short time after the bonnet was closed:cool:

[Roverlord off road spares]

The bracket that holds the bonnet switch is easily bent. Leaning over the vehicle and reaching in to work in the engine bay can sometimes cause you to lean on the bracket , moving it slightly. Then when the bonnet is closed it triggers a miss lock on the switch sounding the horn.
By bending the bracket back to the correct position will often cure the problem of the horn going off.
Cheers,
Mario

[sierrafery]

The bracket that holds the bonnet switch is easily bent. Leaning over the vehicle and reaching in to work in the engine bay can sometimes cause you to lean on the bracket , moving it slightly. Then when the bonnet is closed it triggers a miss lock on the switch sounding the horn.
By bending the bracket back to the correct position will often cure the problem of the horn going off.
Cheers,
Mario
Hi, what you say it's perfectly true but then IMO the misslock on the bonnet would be permannet untill the fix, in this case it goes away after a while by itself or after ignition/unlock command which sends back to my theory though

[rangieman]

The bracket that holds the bonnet switch is easily bent. Leaning over the vehicle and reaching in to work in the engine bay can sometimes cause you to lean on the bracket , moving it slightly. Then when the bonnet is closed it triggers a miss lock on the switch sounding the horn.
By bending the bracket back to the correct position will often cure the problem of the horn going off.
Cheers,
Mario

That Mario is because you have a V8 running on BBQ fuel :p and because it is never running to satisfaction as a BBQ should , Thats why you are forever under the bonnet messing about trying to fix and or bending brackets:wasntme:
Sorry mate could not resist mate:tease:

[Roverlord off road spares]

That Mario is because you have a V8 running on BBQ fuel :p and because it is never running to satisfaction as a BBQ should , Thats why you are forever under the bonnet messing about trying to fix and or bending brackets:wasntme:
Sorry mate could not resist mate:tease:
Says he who doesn't check under the bonnet and blows a hose on his camping trip, so the mighty V8 had to be in pristine condition by regular maintenance to come an do a road side rescue:angel::angel::angel::angel::angel::angel::a ngel:

[clubagreenie]

All this talk and it's a simple cause. It's programmed that way. It's a "tamper" (for lack of a better word) thing. Unlock and open bonnet, close and lock. Horn goes off.

It WILL ALSO go off if a door is not fully closed, the bonnet switch bracket is bent or if the volume sensor is sensing while attempting to lock.

[sierrafery]

I hate to contradict but IMO it's not like that, at least it's nowhere mentioned in any official document and it doesnt happen all the time, i mean the "Unlock and open bonnet, close and lock. Horn goes off." thing , first you can't unlock and open the bonnet cos you have to open the door first to release the bonnet;)

1. It WILL ALSO go off if a door is not fully closed, the bonnet switch bracket is bent
2. or if the volume sensor is sensing while attempting to lock.

about these ^^^ statements:
1. Correct ...provided it's set this way cos the misslock warning can be disabled in BCU...and i've seen some cases when it was
2. that's something strange though cos IMO a volumetric sensor can't feel anything while attempting to lock as the volumetric alarm will be active only after the lock command when the alarm becomes active

[AndrewMilne]

All this talk and it's a simple cause. It's programmed that way. It's a "tamper" (for lack of a better word) thing. Unlock and open bonnet, close and lock. Horn goes off.

It WILL ALSO go off if a door is not fully closed, the bonnet switch bracket is bent or if the volume sensor is sensing while attempting to lock.



Clubagreenie, Can you explain what you mean when you say: "if the volume sensor is sensing while attempting to lock"?


What would what sensor be trying to detect/measure when the engine is not running, and the key is not in the ignition lock?


Just for my education!

[clubagreenie]

The vol sensor detects internal movement, triggers alarm. Not functional (in terms of triggering alarm) when running.

We've had the "Quality of official documentation" discussion ad nauseum in other threads. You can open the bonnet with system "unlocked" and doors not opened. The sensor is active in some capacity as I've had to trace a fault in a system where the sensor was faulty and triggering horn on attempt to lock. Replace, went away. Sit in car waving at it. Duplicate result. Basic scientific process.

[AndrewMilne]

The vol sensor detects internal movement, triggers alarm. Not functional (in terms of triggering alarm) when running.

We've had the "Quality of official documentation" discussion ad nauseum in other threads. You can open the bonnet with system "unlocked" and doors not opened. The sensor is active in some capacity as I've had to trace a fault in a system where the sensor was faulty and triggering horn on attempt to lock. Replace, went away. Sit in car waving at it. Duplicate result. Basic scientific process.

Ah yes, I know the ones you mean, now. They detect air motion inside the car.
I just didn't connect them with the discussion about the horn sounding when doors are locked after the bonnet having been open and closed.
I have had them activate the alarm if I leave windows down a bit when I lock the car, in order not to have the car like an oven when I return. If a gust of wind comes up, they set off the alarm because air moves around inside the vehicle.
I have seen others place sticky tape over them to get around this - I guess it depends on whether having a cooler car inside is more important to you than the risk of not having a car at all!

[sierrafery]

I have had them activate the alarm if I leave windows down a bit when I lock the car, in order not to have the car like an oven when I return. If a gust of wind comes up, they set off the alarm because air moves around inside the vehicle.
....I have seen others place sticky tape over them to get around this - I guess it depends on whether having a cooler car inside is more important to you than the risk of not having a car at all!
It's easy to override that, when you want to leave the windows or the sunroofs opened a bit to let the air move lock with the key in the lock not with the fob, this will disable the ONLY the volumetric alarm(all the rest will be active), it's a built in feature... when you unlock use the fob again...that's all:cool:

[discorevy]

It's easy to override that, when you want to leave the windows or the sunroofs opened a bit to let the air move lock with the key in the lock not with the fob, this will disable the ONLY the volumetric alarm(all the rest will be active), it's a built in feature... when you unlock use the fob again...that's all:cool:
Also handy when dogs in the car on a warm day with windows down
Don't need volumetric sensors with dog in the car anyway (unless it's a Chihuahua :eek:)

[AndrewMilne]

It's easy to override that, when you want to leave the windows or the sunroofs opened a bit to let the air move lock with the key in the lock not with the fob, this will disable the ONLY the volumetric alarm(all the rest will be active), it's a built in feature... when you unlock use the fob again...that's all:cool:
Sierrafery,
What DON'T you know about these vehicles?!
That's a great tip - thank you!
Andrew

[clubagreenie]

Sierrafery,
What DON'T you know about these vehicles?!
That's a great tip - thank you!
Andrew


Everything that isn't in RAVE

[sierrafery]

Don't think it's easy to read 2467 pages... few times:D...as to know them by heart:cool:
1612=workshop manual
712=electrical library
127=circuit diagrams
:cool:

[AndrewMilne]

Don't think it's easy to read 2467 pages... few times:D...as to know them by heart:cool:
1612=workshop manual
712=electrical library
127=circuit diagrams
:cool:


Hi Sierrafery,
I'm sure that is right.
Many times I have noticed your willingness to help anyone with practically anything.
Some may not, but I at least have appreciated it. I daresay that many others do, too.
AndrewM (Western Australia)

[MAF Diver]

The bracket that holds the bonnet switch is easily bent. Leaning over the vehicle and reaching in to work in the engine bay can sometimes cause you to lean on the bracket , moving it slightly. Then when the bonnet is closed it triggers a miss lock on the switch sounding the horn.
By bending the bracket back to the correct position will often cure the problem of the horn going off.


Awesome, will try this! Which one is the bracket tho? :D

[Tins]

Awesome, will try this! Which one is the bracket tho? :D

Near the air box. Rubber covered button on the inner guard. I haven't bent mine.... yet.

[MAF Diver]

Mine looks a bit sad, the top is folded over like a jelly wedding cake

[Tins]

Mine looks a bit sad, the top is folded over like a jelly wedding cake

It's a rubber boot over a fairly simple push button. Can cause problems though.