Question about locks and remotes

I just picked up a new key and programmed it for my Mustang.
Now I wonder... How unique are the keys? And are the keys 'specific'?
Someone once told me GM at some point only had like 50 or 60 different keys.
I'd believe it now. When my Pontiac had a damaged door lock, I went to the junkyard, and within 20 vehicles, I found one with a matching key to pull the lock assembly from.
So... if it were possible to have two Fords, and two matching keys... Could the same transponder key work in two vehicles? Or are there codes that go between the vehicle and the key that make the key/vehicle combination unique?
And the same for the remote. If I happen to have two vehicles that share a similar remote, could I program one remote for both vehicles? To keep from having to carry a pouch for my keychain!
I suppose if I put the same aftermarket remote start in two vehicles, it would depend on the brand and model of the remote start, but with stock Detroit keys and fobs, what are the potentials here?
Mike
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If you are talking about a late model mustang I think there are thousands of electronic IDs for the chip in the key.

In the early years of the GM system that had the little tiny black thing on a regular sized key there were only about 16 different "codes" but you needed both the right code and the right key. I think it would have been at least 400 possible combinations.

I may be doing the statistics wrong but most keys have 5 tumblers in 5 positions so that might be as little as 5x5% combinations. They did switch key blank "grooves" from time to time so that upped the number.

I don't see why it wouldn't work, you'd just program the matching key to each vehicle just like you just did for your new key.

Again, I don't see why not. People lose remotes and buy new ones and program them to a vehicle all the time. In fact, I was going to do that for two of my cars but then realized that with them both parked within 30 feet of each other I would wind up unlocking or locking both when I only wanted to do one of them.

See above.
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Remotes today have nothing to do with the tumblers. The is a logarithmic chip, in the key, that must be programmed for the particular vehicle.
My 2010 Lincoln MKZ will unlock, and start my car, as I approach it with the key in my pocket.
I must insert the key when I get in, or it will stop and not restart, if I apply the brake.
wrote:

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I think I'm going to have to get out my work tools and find out...
Anyone know if the car keys are RFIF like at 13.56Mhz? 14443a/b? 15563? LF? UHF?
Hmm, I have the cabibility of looking at a lot of 13.56MHz stuff. I may take my keys into the lab... Hey, if I can read my passport, I can certainly read a key! Well, at least I used to be able to... Until it was soaked in the Igauzu River...
I wonder... Is your key one of those new ones that has buttons on the key itself? My Mustang just used a plain 'transponder' key.
Mike
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He asked about both keys and remotes. My comments on tumblers related to his questions on keys.

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Whet makes you think I was rely to what you said? I was replying to the question asked.
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Because you replied to my post, not his.

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wrote:

I realize that. Somewhere around 64Million combinations.

If I remember right, the 'chip' in the key only had about 5 different values. And it was just a resistor.

But GM didn't use them all. Not even close. And there are lot of combinations that CANNOT be used for practical reasons. For example, you cannot have a key that has decreasing steps to the end, or the key could fall out in operation. And I don't think they use 5 steps, otherwise the tumbler would be WAY too susceptible to bounce (look up 'bump key' sometime)

You're missing the point. The key MAY not just be presenting a 'serial number' to the vehicle. And that's my question. DOES the key just present it's 'serial number' to the vehicle receiver, or is there interaction?

Remotes in some cases are actually MORE secure than the keys. Some remotes, especially the aftermarkets, are bidirectional in that when used the vehicle transmits BACK to the remote. Then the next time the remote is used, it has to know a NEW 'token' to send to the vehicle. Some aftermarket remotes actually WILL work multiple vehicles, and know how to keep multiple tokens from multiple vehicles 'straight' without getting confused. The remote start system I bought my girlfriend for her Jeep does this. In fact, the optional remote even has an LCD screen that will tell her the internal air temp of the car. It not only can be programmed to work with multiple cars, it can even be programmed to to work with some home security systems, so you have one remote for everything.

I guess you don't know...
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One might have to ask in what manner do you consider the key "unique"? The electronic security measures are far more effective than physical security measures.
Of interesting note.... while the key itself has 7 "notches', not all of the notches are used at the same time. A key that can open your door likely wont operate the ignition and vice versa. Sorry, I can't remember the exact assignments but, IIRC, fewer notches are used for door security than ignition security.
FWIW, Ford has stopped including steering column locks on some marques.
Words to the wise - always have 3 keys available... should one become lost or damaged, you can still program your own spare key. Having said that, it is still wise to visit the dealer or another shop that can manage "PATS fuctions". Should a key be lost or stolen, it's electronic signature can (and should) be erased from memory. If some low-life is lucky enough to find both car and key, the worst that can happen is that he will gain entry.
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