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View Full Version : How does this key/lock work?


Absolute
03-29-2004, 07:02 PM
I have a 2003 BMW, and I've been wondering how the key works.

Instead of having bumps cut into its edges, it has a grooved pattern carved onto the flat top and bottom. The pattern is identical on both sides, presumably so that it can be inserted either way. I've never seen anything like it before, and I'm wondering how the lock mechanism works. Anyone know?

This same key works for the doors, ignition, trunk, and glove box, so I doubt it's anything too complicated.

Here's a picture: http://www.amityregion5.org/key.jpg

Chefguy
03-29-2004, 07:18 PM
It's probably got an anti-theft chip imbedded in the key. The car won't run without sensing the chip. That's why you need to keep the code where you can find it, in case you lose the key. They can't cut a new one at the local hardware store.

GaryM
03-29-2004, 07:20 PM
Most keys work by having the highs and lows of the key move the pins so that their cuts line up with the cylinder so that the cylinder is free to rotate and operate the locking mechanism.

This is a guess, so don't yell if it's wrong!

Your key has "waves" cut into the side of the key. It could be that the pins have an "L" shape that rides in the waves thereby raising the pins so the cylinder can rotate. After that it's no different than any other lock.

Absolute
03-29-2004, 07:37 PM
It's probably got an anti-theft chip imbedded in the key. The car won't run without sensing the chip. That's why you need to keep the code where you can find it, in case you lose the key. They can't cut a new one at the local hardware store.
I was wondering about the physical design of the key itself, not the electronics. But you have me worried: I never got a code with the car, just two keys. The other one looks identical to the one I took a photo of. Should I ask the dealer to give me the code, in case something happens to both the keys?

What would I do with the code, assuming I had it but had lost the keys?

Kaotic Newtral
03-29-2004, 08:13 PM
I was wondering about the physical design of the key itself, not the electronics. But you have me worried: I never got a code with the car, just two keys. The other one looks identical to the one I took a photo of. Should I ask the dealer to give me the code, in case something happens to both the keys?

What would I do with the code, assuming I had it but had lost the keys?

I've had the same problem before. The only way I could get a new key mastered was to get the dealership to recode one. IIRC it cost me a pretty good penny, I think around $65 US. This is a 1999 Mustang Cobra though...YMMV but I couldn't get the code ahead of time.

butler1850
03-29-2004, 08:18 PM
Gary has the mechanism correct.

The code is retrieved via your VIN number, any dealership can look up which key you have, and make you a new set.

You may have the code, however, somewhere in the beginning of your owners manual (if you got it new, or the previous owner still had it.)

TJdude825
03-29-2004, 08:39 PM
Most keys work by having the highs and lows of the key move the pins so that their cuts line up with the cylinder so that the cylinder is free to rotate and operate the locking mechanism.

This is a guess, so don't yell if it's wrong!

Your key has "waves" cut into the side of the key. It could be that the pins have an "L" shape that rides in the waves thereby raising the pins so the cylinder can rotate. After that it's no different than any other lock.

Sounds most logical to me. If that's right, you might hear a little bit of clicking, and feel a tiny bit of resistance, as the curviest parts of the groove reach the pings. OTOH, the groove looks smooth enough that you might not. But if you do, I'd say that's some pretty good evidence that GaryM is right.

BTW, I'd guess they did it this way so that it's harder to injure someone with a key accidentally.

gotpasswords
03-29-2004, 09:00 PM
IANALocksmith, but another possibility is that the wave design allows for a "double cut" sort of action, where there are tumblers on both sides - in other words, one set of tumblers is pushed into position and the other is pulled into position. This greatly complicates lock-picking.

yabob
03-29-2004, 09:03 PM
The key style is sometimes called a "sidewinder" key, and is intended as a security measure - the arrangement makes the locks difficult to pick (and prevents them from being duplicated on ubiquitous hardware store machines - you need a special milling machine). It is often used in conjunction with a transponder, as noted.

These are mentioned for sake of inclusion in the discussion, but they have no bearing on the subject of lockpicking as they are virtually pick proof. Found in many of the luxury cars of late (and going back decades on some German models), you can recognize locks that use them by the unusually wide and square keyway, and by the key. Keys are referred to as "sidewinder" keys (there are a few other kinds as well, equally bizarre looking). They do not have "teeth", or profile cuts, as do normal keys but rather a crooked, milled groove along the flat of the key blade. While picking is not entirely impossible, it is deemed entirely inappropriate due to the very small likelihood of success.
From a page on lockpicking, not linked because it would just get edited out anyway.

If you look around under "sidewinder key", you will find various key and lock services that deal with them, as well as with programming key transponders.

AllShookDown
03-30-2004, 01:28 PM
What would I do with the code, assuming I had it but had lost the keys?

When I picked up my new car last week I was told that the dealer can use the code to make a key to get into the car if you've locked yourself out. The key wouldn't start the car though because it wouldn't have the chip. I don't know if the code does you any good if you've lost the keys.