Weird Trunk Behavior

bacampbe · 01-03-2015, 01:09 PM

Our 2012 328i has the comfort access feature to open the trunk with your foot. Once we figured out the proper technique, it has worked flawlessly until now.

On NYE, I loaded some items in the trunk. When I went to close it, it immediately reopened, after going through the light flash sequence. This happened several times. It almost seemed like the foot-sensor had become hyper-sensitive. I finally tried immediately stepping away from the car, and it stayed closed. But when I approached, it opened again. Finally, I was able to "sneak" up on the car, and go my way. Afterwards, it seemed to return to normal operation.

Last night, it seemed to have stopped working entirely. Other methods (the trunk sill button and the fob button) continued to work fine. After driving across town to a friend's house, it still would not work. But when we left a few hours later, it started working again. Now it seems fine.

We have had cold (for Dallas) rainy weather lately, but the car is garaged, and both events occurred after the car had been in the garage for 24 hours.

Has anyone else experienced this, or otherwise have thoughts about it? I realize the answer is "take it to the dealer." But I also know how things tend to go with dealers when you hand them intermittent problems.

Tony M · 01-03-2015, 06:28 PM

Sorry, can't help with the same problem. However, I have noticed a slightly different one.

My trunk opens fine with the kick action - I reckon I've got it to about 95 to 99% with practice. However, it also opens consistently when I'm washing the car and I'm cleaning the chrome exhaust tips. This remained unchanged when I substituted the M-performance muffler.

Anyone else with ticklish/oversensitive exhaust tips?

34.50 · 01-03-2015, 08:57 PM

Quote:

Originally Posted by Tony M

My trunk opens fine with the kick action - I reckon I've got it to about 95 to 99% with practice. However, it also opens consistently when I'm washing the car and I'm cleaning the chrome exhaust tips. This remained unchanged when I substituted the M-performance muffler.

You can lock the trunk from being opened in car washes - there is a switch in the glove box. I do that when I'm going through touchless car washes/doing hand washes.

Fronzdan · 01-03-2015, 08:57 PM

OP, are you sure there's not anything stuck under there...a leaf, paper or something? Look for the sensor and wash it off maybe?

As for it opening when washing...that's "normal" operation if you have your key in your pocket. Water dripping on the door handles or down the back of the trunk will cause it to open. If you're back there polishing your exhaust tips, that motion could be enough to trigger it. Now if your key isn't on you and it opens...THAT IS A PROBLEM.

Ali Shiralian · 01-03-2015, 10:48 PM

Quote:

Originally Posted by Tony M

Sorry, can't help with the same problem. However, I have noticed a slightly different one.

My trunk opens fine with the kick action - I reckon I've got it to about 95 to 99% with practice. However, it also opens consistently when I'm washing the car and I'm cleaning the chrome exhaust tips. This remained unchanged when I substituted the M-performance muffler.

Anyone else with ticklish/oversensitive exhaust tips?

Is the key fob in your pants pocket by any chance? It happened to me a few times cleaning the chrome exhust tips, then I realized my thigh was pressing the button

bacampbe · 01-03-2015, 11:32 PM

Quote:

Originally Posted by Ali Shiralian

Is the key fob in your pants pocket by any chance? It happened to me a few times cleaning the chrome exhust tips, then I realized my thigh was pressing the button

One should be able to tell the difference. After a software update a few months ago, if you "kick" it open, it delays and flashes the tail lights before opening. If you open it with the fob, it just opens immediately with no fanfare.

Tony M · 01-04-2015, 08:02 AM

Quote:

Originally Posted by 34.50

You can lock the trunk from being opened in car washes - there is a switch in the glove box. I do that when I'm going through touchless car washes/doing hand washes.

I don't believe the 4 series has this trunk lockout switch, which i understood was for valet parking security.

Quote:

Originally Posted by Fronzdan

As for it opening when washing...that's "normal" operation if you have your key in your pocket. Water dripping on the door handles or down the back of the trunk will cause it to open. If you're back there polishing your exhaust tips, that motion could be enough to trigger it. Now if your key isn't on you and it opens...THAT IS A PROBLEM.

Yes, I have the key in my pocket when washing the car. I have noticed the door handles react to cleaning and keep locking and unlocking the car, but that's to be expected as they are designed to react to touch. The trunk sensors are designed to react to a specific kicking action that is quite unlike polishing the exhaust tips.

Quote:

Originally Posted by Ali Shiralian

Is the key fob in your pants pocket by any chance? It happened to me a few times cleaning the chrome exhust tips, then I realized my thigh was pressing the button

No, the button on the fob is not being pressed.

Quote:

Originally Posted by bacampbe

One should be able to tell the difference. After a software update a few months ago, if you "kick" it open, it delays and flashes the tail lights before opening. If you open it with the fob, it just opens immediately with no fanfare.

Yes, when I clean the exhaust tips, I know I've triggered the trunk opening before it happens as the lights flash first. It's funny that it took me ages to perfect the kick motion, but I keep opening it by accident just by rubbing a wet cloth over the exhaust tips, most of which are not even under the car but sticking out the back. I'd like to know if it's the sensor reacting in way it's not designed to do or some other phenomenon. I'll have to do some experimentation to try to narrow it down - eg, I'm not sure if it still does it if water isn't involved.

Fronzdan · 01-04-2015, 11:38 AM

Yes you'd think the trunk sensor would only react to a kicking motion. But I have had the fob in my pocket and while rinsing the rear end with the hose, the trunk has falsely detected a foot swipe and opened the trunk. I actually sprayed some water in the trunk it happened so unexpectedly. So when I say it's "normal", I don't mean that's expected behavior. But it happens.

Now I never keep the fob on me when detailing.

01-03-2015, 01:09 PM	#1
bacampbe Lieutenant 348 Rep 530 Posts Drives: 2024 Z4 M40i PB Join Date: Jun 2012 Location: Dallas, TX iTrader: (0)	Weird Trunk Behavior Our 2012 328i has the comfort access feature to open the trunk with your foot. Once we figured out the proper technique, it has worked flawlessly until now. On NYE, I loaded some items in the trunk. When I went to close it, it immediately reopened, after going through the light flash sequence. This happened several times. It almost seemed like the foot-sensor had become hyper-sensitive. I finally tried immediately stepping away from the car, and it stayed closed. But when I approached, it opened again. Finally, I was able to "sneak" up on the car, and go my way. Afterwards, it seemed to return to normal operation. Last night, it seemed to have stopped working entirely. Other methods (the trunk sill button and the fob button) continued to work fine. After driving across town to a friend's house, it still would not work. But when we left a few hours later, it started working again. Now it seems fine. We have had cold (for Dallas) rainy weather lately, but the car is garaged, and both events occurred after the car had been in the garage for 24 hours. Has anyone else experienced this, or otherwise have thoughts about it? I realize the answer is "take it to the dealer." But I also know how things tend to go with dealers when you hand them intermittent problems.
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01-03-2015, 06:28 PM	#2
Tony M Enlisted Member 5 Rep 34 Posts Drives: 428i Coupe Join Date: Jul 2014 Location: Australia iTrader: (0)	Sorry, can't help with the same problem. However, I have noticed a slightly different one. My trunk opens fine with the kick action - I reckon I've got it to about 95 to 99% with practice. However, it also opens consistently when I'm washing the car and I'm cleaning the chrome exhaust tips. This remained unchanged when I substituted the M-performance muffler. Anyone else with ticklish/oversensitive exhaust tips?
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01-03-2015, 08:57 PM	#4
Fronzdan Lieutenant Colonel 304 Rep 1,739 Posts Drives: '24 M240 xDrive Join Date: Mar 2014 Location: MA iTrader: (0)	OP, are you sure there's not anything stuck under there...a leaf, paper or something? Look for the sensor and wash it off maybe? As for it opening when washing...that's "normal" operation if you have your key in your pocket. Water dripping on the door handles or down the back of the trunk will cause it to open. If you're back there polishing your exhaust tips, that motion could be enough to trigger it. Now if your key isn't on you and it opens...THAT IS A PROBLEM.
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01-04-2015, 11:38 AM	#8
Fronzdan Lieutenant Colonel 304 Rep 1,739 Posts Drives: '24 M240 xDrive Join Date: Mar 2014 Location: MA iTrader: (0)	Yes you'd think the trunk sensor would only react to a kicking motion. But I have had the fob in my pocket and while rinsing the rear end with the hose, the trunk has falsely detected a foot swipe and opened the trunk. I actually sprayed some water in the trunk it happened so unexpectedly. So when I say it's "normal", I don't mean that's expected behavior. But it happens. Now I never keep the fob on me when detailing.
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