Locking the trunk

I usually keep my trunk locked because of a previous break-in on my Accord. The thieves busted a window, popped the trunk, and made off with its contents.

I was wondering if there's a need to lock the trunk in the E46. If I leave the trunk unlocked but lock and arm the alarm, will thieves be able to open the trunk by busting in and pressing the trunk release button? Or can they unlock all the doors by pressing the door unlock button and then access the trunk by the release mechanism under the trunk? Would leaving the trunk locked make it harder to physically pry it open?

Long post short: Is the trunk lock feature just to prevent valets (read: those with non-master keys) from accessing the trunk, or is it to prevent thieves from breaking in as well?

TIA.

Originally Posted by swchang

If I leave the trunk unlocked but lock and arm the alarm, will thieves be able to open the trunk by busting in and pressing the trunk release button?

How do you lock and arm your alarm without also locking your trunk?

Alex

When you arm your alarm, all doors and the trunk are locked, but a thief could punch the door lock, and get into trunk by pushing the trunk release button. If you lock the trunk by physically using your key (manual lock), the trunk can only be unlocked by the key. When you manually lock the trunk, it disables all the electronic means that could otherwise unlock the trunk.

Originally Posted by BahnBaum

How do you lock and arm your alarm without also locking your trunk?

Alex

I meant where you put the key in and physically lock it.

Originally Posted by gfeiner

When you arm your alarm, all doors and the trunk are locked, but a thief could punch the door lock, and get into trunk by pushing the trunk release button. If you lock the trunk by physically using your key (manual lock), the trunk can only be unlocked by the key. When you manually lock the trunk, it disables all the electronic means that could otherwise unlock the trunk.

Punch the door lock? What's that?

So even without a key, you can still activate the electronic trunk release if you can get into the car somehow? If that's the case, I guess I'll be keeping my trunk locked after all... Sigh, I was hoping not to have to do that, because sometimes when I drop someone off they need to get into the trunk. It's a real pain to have to turn the engine off each time since the electronic release button won't open a locked trunk, and the remote control trunk release won't work when the key's in the ignition.

If your car alarm is programmed such that is can be disabled if you unlock the driver door with a key, then a thief could punch (force) the lock open with a screw driver which would disable the alarm. The alarm can't tell if the door lock was punched or opened with a key. Once inside with the alarm disabled, the theif could use the trunk release to open the trunk. But if you locked the trunk with the key, the trunk release would not work.
I recently got my alarm programmed so that it can only be disabled by using the remote.

Originally Posted by gfeiner

I recently got my alarm programmed so that it can only be disabled by using the remote.

And under these circumstances, the interior central locking switch and trunk release switch are disabled. There is no way short of physically prying (the hell out of) the trunk lid to open it when the system is locked and armed.

Originally Posted by RKT BMR

And under these circumstances, the interior central locking switch and trunk release switch are disabled. There is no way short of physically prying (the hell out of) the trunk lid to open it when the system is locked and armed.

Not true, when my alarm is armed, I can open the trunk by manually unlocking it with my key, but of course that sets off the alarm.

Originally Posted by gfeiner

Not true, when my alarm is armed, I can open the trunk by manually unlocking it with my key, but of course that sets off the alarm.

So you're saying that you CAN open the trunk by pressing the button on the inside of the car EVEN IF you don't have a key, simply by punching the lock cylinder through. However, this only works if the alarm is programmed to be deactivated with a key, not if it's programmed to be deactivated only with the alarm?

No. I was saying when your alarm is coded only to be engaged/disengaged by the remote, the only way you can open the trunk while the alarm is armed is by physically sticking your key in the trunk lock and unlocking it the old fashioned way. But doing so will set off the alarm, because the alarm (in my case) can only be disarmed by pressing the disarm button on the remote.

It's kind of like using the glove compartment lock - if the you manually lock the trunk (turn the key to the horizontal position, it will not open when the central door locks or the trunk release (on the key fob or in the car release) are hit. I don't think any electronic release can override the manual lock you can do.

Originally Posted by swchang

Long post short: Is the trunk lock feature just to prevent valets (read: those with non-master keys) from accessing the trunk, or is it to prevent thieves from breaking in as well?

TIA.

Originally Posted by palooka666

It's kind of like using the glove compartment lock - if the you manually lock the trunk (turn the key to the horizontal position, it will not open when the central door locks or the trunk release (on the key fob or in the car release) are hit. I don't think any electronic release can override the manual lock you can do.

Right, but more specifically I was wondering if a non-manually locked trunk could be opened if someone broke into the car. From gfeiner's replies, it seems that it can if your alarm is set to deactivate via key, but even then only if your door cylinder is punched to deactivate the alarm. If the alarm is still going off or if your setting is on remote disarm only, from what I've gleaned of the posts, it cannot.

Originally Posted by swchang

Right, but more specifically I was wondering if a non-manually locked trunk could be opened if someone broke into the car. From gfeiner's replies, it seems that it can if your alarm is set to deactivate via key, but even then only if your door cylinder is punched to deactivate the alarm. If the alarm is still going off or if your setting is on remote disarm only, from what I've gleaned of the posts, it cannot.

You could try it out by leaving the driver's side window open, then lock the car and arm the alarm. wait more than 20 seconds (i'd wait a minute) then reach in to the car and try and unlock the truck by hitting the release... Then try opening the trunk with the trunk release handle (rubber thing under the handle)... do lock the car and arm it again and try again by reaching in and hitting the central door locks.

Either way, your motion sensor should set off your alarm. That's how i tested my alarm after I DIY'd it. I figure this will let you get to your answer.

Originally Posted by gfeiner

Not true, when my alarm is armed, I can open the trunk by manually unlocking it with my key, but of course that sets off the alarm.

Sorry for the confusion... Of course you can open it with the key -- both manually, and with the remote button on the key.

I was referring to the possibility of opening it without the key, which is what I thought the point of the thread was about.

Also, opening the trunk manually with the key with the alarm armed should not set off your alarm. There's a microswitch in the cylinder mechanism that is supposed to handle this. You should get it checked by the dealer.

Originally Posted by palooka666

You could try it out by leaving the driver's side window open, then lock the car and arm the alarm. wait more than 20 seconds (i'd wait a minute) then reach in to the car and try and unlock the truck by hitting the release... Then try opening the trunk with the trunk release handle (rubber thing under the handle)... do lock the car and arm it again and try again by reaching in and hitting the central door locks.

Either way, your motion sensor should set off your alarm. That's how i tested my alarm after I DIY'd it. I figure this will let you get to your answer.

Hit the lock button twice on the key to arm the alarm, but disarm the motion and tilt sensors.

Then reach in that open driver's window and try to pop the trunk with the interior release switch near the hood release. The trunk will not open.

Okay, now I'm confused. Here are some scenarios to consider...

These I'm certain about***********:

1) car either locked or unlocked; trunk locked: UNable to open trunk by trunk button or interior release
2) car unlocked; trunk unlocked: able to open trunk by trunk button or interior release (obviously)

These I'm uncertain about***********:

3) car locked, sensors armed; trunk unlocked
4) car locked, sensors unarmed; trunk unlocked

RKT BMR and gfeiner, are you saying the same thing? If doors locked, thief breaks in, no way to open trunk with release buttons UNLESS you can trick the car into thinking it was opened by a key (as in punching in the door cylinder)? Therefore, a thief breaking in through the window can't open the trunk, even if left unlocked, while a thief who punches in the lock cylinder can only open it if the alarm was set to be disabled by key?

Phew, that was a mouthful... Anyway, is that right?

Originally Posted by swchang

RKT BMR and gfeiner, are you saying the same thing? If doors locked, thief breaks in, no way to open trunk with release buttons UNLESS you can trick the car into thinking it was opened by a key (as in punching in the door cylinder)? Therefore, a thief breaking in through the window can't open the trunk, even if left unlocked, while a thief who punches in the lock cylinder can only open it if the alarm was set to be disabled by key?

Put simply, if the state of the electronic systems responsible for the locking behavior of the car is that the whole car is "locked" (regardless of whether or not there is an alarm installed), electronic means to open the trunk will not function. This means the paddle switch under the exterior handle on the trunk, and the interior switch in the lower left driver's footwell.

By "locked" condition I am referring to the mode where all doors are double-locked (i.e., they can't be opened from the inside with the chrome handle), and the fuel filler door is locked. See the manual for a description of the various locking modes of the central locking system.

Put simply, this is the state achieved when locked from the outside with either the BMW logo locking button on the key, or manual locking from the driver's door cylinder rotating the key clockwise.

If an alarm is installed, this will also arm the alarm.

If a thief can change the lock state of the vehicle by punching out the door cylinder, putting the vehicle into a state of "unlocked", then the interior trunk release will work. This is the reason that there is a configurable car memory option for disabling the key cylinder as a means of changing this state in the central locking system electronics.

I hope that clears it up. Please post any other clarifying questions, and I'll do my best to answer them.

I think that clarifies it. Thanks a lot!

Oh, actually, one thing gfeiner said still puzzles me. He said that if you disable disarming by key, you can't open a locked trunk except by using your key? So you can't use the remote to pop it anymore?

Originally Posted by swchang

I think that clarifies it. Thanks a lot!

Oh, actually, one thing gfeiner said still puzzles me. He said that if you disable disarming by key, you can't open a locked trunk except by using your key? So you can't use the remote to pop it anymore?

A bit confused by "disable disarming"... Do you mean disable arming of the motion and tilt sensors?

Regardless, gfeiner is incorrect if he stated or implied that the trunk can not be opened with the remote trunk release on the regular key. That should always work, no matter how you've locked the car.

The valet security works a bit differently on the convertible vs. the coupe and sedan, but the basic operation is the same -- difference is in how you enable it.

On the coupe and sedan, valet security is enabled by using the regular key to turn the trunk lock cylinder to a secured position CCW. This doesn't actually do anything mechanically; all it does is activate a hall sensor in the lock mechanism that the Central Locking System, managed by a computer module in the car called the General Module V (GMV), detects and then knows to ignore open signals from the exterior switch on the trunk handle, and the interior trunk opening switch.

On a convertible, the same feature is enabled by locking the glovebox with the regular key.

The valet key (whether metal or plastic) has a slightly different, shallower groove cut in to it on the sides, and the trunk and glovebox lock cylinders are slightly different than the door and steering column lock cylinders, such that the shallower groove wont allow the key to fit in the trunk and glovebox lock cylinders.

Regardless, no matter how you set the trunk (coupe/sedan) or glovebox (convertible) lock cylinder, the trunk release on the regular keys will always open the trunk. Try it out.

Originally Posted by RKT BMR

A bit confused by "disable disarming"... Do you mean disable arming of the motion and tilt sensors?

Regardless, gfeiner is incorrect if he stated or implied that the trunk can not be opened with the remote trunk release on the regular key. That should always work, no matter how you've locked the car.

The valet security works a bit differently on the convertible vs. the coupe and sedan, but the basic operation is the same -- difference is in how you enable it.

On the coupe and sedan, valet security is enabled by using the regular key to turn the trunk lock cylinder to a secured position CCW. This doesn't actually do anything mechanically; all it does is activate a hall sensor in the lock mechanism that the Central Locking System, managed by a computer module in the car called the General Module V (GMV), detects and then knows to ignore open signals from the exterior switch on the trunk handle, and the interior trunk opening switch.

On a convertible, the same feature is enabled by locking the glovebox with the regular key.

The valet key (whether metal or plastic) has a slightly different, shallower groove cut in to it on the sides, and the trunk and glovebox lock cylinders are slightly different than the door and steering column lock cylinders, such that the shallower groove wont allow the key to fit in the trunk and glovebox lock cylinders.

Regardless, no matter how you set the trunk (coupe/sedan) or glovebox (convertible) lock cylinder, the trunk release on the regular keys will always open the trunk. Try it out.

"Disable disarming by key," as in the setting whereby you disable the ability to disarm the alarm by a key. You can only do it with the remote. That's what I meant.

Yeah, I know about the valet thing and being able to open even a locked trunk with the remote. I was just wondering if the alarm would sound if you did that when you open a locked trunk with the remote when the setting "disable disarming by key" is enabled, like gfeiner said it would. That's all.

Originally Posted by swchang

"Disable disarming by key," as in the setting whereby you disable the ability to disarm the alarm by a key. You can only do it with the remote. That's what I meant.

Yeah, I know about the valet thing and being able to open even a locked trunk with the remote. I was just wondering if the alarm would sound if you did that when you open a locked trunk with the remote when the setting "disable disarming by key" is enabled, like gfeiner said it would. That's all.

Got it

And don't know the answer However, I'd be real surprised if the alarm did go off with a remote pop of the trunk under these circumstances.

Here's a thread from e46fanactics about a guy who had the lock punched on his 330 and the alarm didn't go off because it was set to disable by both key and remote.

http://forum.e46fanatics.com/showthread.php?t=158346

The problem with the OEM alarm is that it can't tell if the door lock was opened with a key or forced opened/punched/popped with a screw driver.