CASL55

The keys to my two Mercedes are identical to me, but not to the cars. I've got them on different places on the key ring, but I sometimes try to use the wrong one.

Can the dealer make adjustments to allow me to use one of the keys to operate both vehicles? You'd think they'd want to encourage you to have as many MBs as possible, and a pocketfull of identical keys wouldn't be much fun.

Jim

Omegaonne

Hmmm.... I don't think so, but would that be a great line when you want to impress the girl you're on a date with?

HELL ONA HARLEY

Two different key fobs would do the trick.....ya think???

sosh

Can't be done

Omegaonne

Too Bad

Hey Sosh, are u an eagles fan? Good luck on sunday

BudC

BMW provide colored stickers for their keys so you can tell them apart. There should be some way to do that with Mercedes smart keys.

t-bone

The little grooved tab on the smart key can be changed to a few different colors. It's the tab that you push on in order to pop out the mechanical key. Some colors that I know of are red, green, blue, black, and grey. There may be more but I'm not sure.

BudC

Thanks for the tip. I just checked and we've got grey and black. I guess I would have noticed if the colors were brighter.

DWP

If you have touch-up paint for both cars, and assuming that the colors are different, you could paint the keys a little with the corresponding paint. You could also put a small glob of epoxy on one key to tell them apart by touch.

MBE55AMG

It can't and shouldn't be done. Basically, if you get that "2-keys-in-one" stolen, you're in for some deep trouble and off without a spare key for either one of your cars. I'm sure none of us want that.

CASL55

Everybody seems to agree that it can't be done. Thanks to all for the input.

As to whether it should be done or not, I still think it would be a great convenience. There's nothing to say that MB couldn't give you several keys that each operate two cars, so having a key stolen wouldn't be any more inconvienent than if the key operated only one car.

Now that we're on the subject, does anyone know how the MB keys work? I assume they're communicating electronically with the car, but is it conductive? Or optical? Or radio? What's the protocol like? Does the car interrogate the key, or does the key just blast out a code?

Jim

chem0

i would want that if i was the one who stole it c'mon! SL55 and wagon!!

miroj

It would cost a lot of time and money to do it and would essentially make it easier for someone to steal both cars. I expect that having keyless go on both cars would be a good place to start ..... but still a waste of money. You couldnt for example lock one car and open the other ... unless it was Keyless Go.

Marking the keys with coloured tabs makes it simple.

BudC

OK, here's my understanding of how it works. As each car is manufactured it is set up to use one of seven different key codes. Those seven codes go into a computer at the factory. Keys that work with the original code are provided with the car when you purchase it. No other car shares those seven codes....NONE!

Now if you lose a key, the factory will supply a key for the next code in sequence and the dealer will change the code in the car to the new code.

All the dealer can do is select one of the seven predetermined codes and cancel a code that had been used (to prevent a stolen key from being used).

If all of the seven codes get used then there apparently has to be a major change to the car to accept seven new codes. The sequence will start over in this situation.

Apparently Mercedes got some bad publicity in the past about vehicle theft (even though Mercedes were and are the toughest to steal). This is their reaction. As usual, Mercedes came up with something pretty far out.

scorchie

That's weird that it can't be done. Because on my 300E (W124), it uses two keys to operate it (one for the ignition and one for the door... they are different). I would think that if that's the case, then on other cars you could use one key for two cars.

-s-

BudC

Read my post above. It's not what they could have done, it's what they did do.

glojo

Mercedes usually have 'Smart' drivers. After all they have built the Smart car:

http://www.thesmart.co.uk/

Regards,
John

BudC

Well, it turns out that the Smart keys are marked. Mine are grey and black. It's the slide for the Valet key (which isn't a Valet key in the U.S.).

miroj

Its not a garage door. The car computer is marked with the personality of the key and the key is marked with the personality of the car. It is a mutually shared code with combined passwords.

Did you ever tinker with PGP as an email protector ? A bit like that !

You can attach as many as 7 keys to a car but each key is limited to the code it can associate with. Therefore if you would be silly enough to modify your car then it is possible.

Fundamentally it is easiest with two identical cars ...... from there on it may want to be the same engine ..... and from then on any differences ar4e just annoying.

Personally I would call the dealer and order the next two cars thus.

BudC

I seriously doubt you can order two cars that will share the same key code. I thought I'd explained this pretty well but I guess I haven't.

If anyone has ordered a key for an older car recently you'll know that Mercedes have really become paranoid about this business. My wife lost her key to our 300E. I had to drive all the way over to the other side of the Valley to present myself to the dealer and provide both my driver's license and proof of ownership.

These were Zerox'ed and sent along to MBUSA with the order for a new key.

When the key came in, I had to drive over there again and go through the same process.

They aren't fooling around.

At one time all I had to do was call the dealer and give him my Vin number. When the key came in, I just went and picked it up.

miroj

I dont think you realise how easy it is to steal a Mercedes ..... going all huff-puff over the keys is trivial. Im not interested in helping anyone find out how but I realise this is not "secret" since there are several gangs operating in Sydney who boost AMG cars without breaking anything.

Probably has more to do with that movie with the laser cut keys from Hamburg.

BudC

I haven't said anything about how well Mercedes system works, only about how it works. In any case, all you need to steal most American or Japanese cars is a screwdriver.

In fact, all you need is the Vin number and a dealer will cut you a new key.

JimPurdy

There are multiple issues here. The key usually opens the door with a radio pulse that a reciever in the car reads. The key is programmed to "talk" to this reciever. I suppose the car reciever could be reprogrammed to "listen" for a different key. The ignition recepticle uses infrared to read a bar code inside the key. Remember the old 202 and 210 models that came with an emergency key that didn't have the transmitter but had the valet key and would start the car? That key had the bar code inside so the car could read it and start. Again, the car computer would have to be reprogrammed. Now, the door and other physical locks would have to be changed to match the different valet key. This would be a lot of change to the car, not the key, to make one key work for multiple cars.

Jim

miroj

The car retains code from the key and the key retains code from the car.

CASL55

Now, that makes sense to me. So the only way to get the car to start would be to feed it one of the bar codes that it's looking for. So you'd have to have the key present two bar codes at different times, which is not the way it's designed. Presumably, the car doesn't interrogate the key in any way that can uniquely identify the vehicle, so even a new design of the key couldn't automagically identify the car and give it the bar code it's looking for.

Sure sounds it like can't be done. Thanks for the insight into the design of the system.

Jimm