Why don't identical keys work with different cars? (alarm, Japanese, chip)
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Cars that are of the same make and model usually have keys that are identical in shape. You can insert one car's key into the other, and it will fit perfectly, but the door still won't turn and the ignition still won't turn/start.
Why is this?
Is it the computer?
So if you disconnected the battery, would any key that fit the lock's mold perfectly turn? And would the ignition turn (not start obviously)?
If it isn't the computer, how are they doing this?
You're thinking the old school "keys" physical characteristics (cuts) is what makes them different. Today, "keys" may look the exactly the same but the electronics of that "key" is what makes them different. Ever wonder why a simple key that once was cut at any hardware store or corner key stand for a couple dollars now cost hundreds?
In the 1950s, Fords came with only about five or ten different keys. Walk into a parking lot with a dozen random new Fords, and your Ford key will start a couple of them.
A certain measure of security came from the difference in the door key, which was separate from the ignition key. The odds went up to about 100:1 that both your door key and ignition key would fit another car. But in those days, few people actually locked their doors.
A mechanical key has long grooves in the sides, which enable it to slide into a lock, and teeth in one edge which enable it to be turned against the position of tumblers inside the lock. If the key fits into the slot and then turns the lock when you get it in there, it has worked and unlocked the mechanical assembly. Whether or not there are electronic components depends on chips embedded in the system.
Cars that are of the same make and model usually have keys that are identical in shape. You can insert one car's key into the other, and it will fit perfectly, but the door still won't turn and the ignition still won't turn/start.
Why is this?
Is it the computer?
So if you disconnected the battery, would any key that fit the lock's mold perfectly turn? And would the ignition turn (not start obviously)?
If it isn't the computer, how are they doing this?
Thanks!
Your question does not involve the chip keys of more recent cars so I'll ignore the chips and talk about old school keys that are strictly mechanical:
You are talking about keys having the same "warding" but not the same "cut". The "warding" is the set of grooves in the sides of the key, that determine if a particular key will enter a particular lock.
The "cut" is the set of ridges on the edge of the key, that position the tumblers at the correct depth so the cylinder will rotate.
Yeah, not only older Fords, but many Japanese cars, and particularly bikes, of the 70's only had a few keys out there, so if you had a key to a similar model, it could easily fit several bikes or cars.
Occasionally, back in those days, when most Japanese cars only had a few different options and colors, people would get into a car similar to their own but it's not their car, but the key fit and they drove off in it. Usually would figure it out when they noticed that their "stuff" was not in the car, but another person's stuff was.
You're thinking the old school "keys" physical characteristics (cuts) is what makes them different. Today, "keys" may look the exactly the same but the electronics of that "key" is what makes them different. Ever wonder why a simple key that once was cut at any hardware store or corner key stand for a couple dollars now cost hundreds?
Quote:
Originally Posted by notnamed
If they were truly identical the door lock would turn just fine and open it. The chip in the key just comes into place for the alarm/immobilizer.
The keys I'm thinking of have the exact same "look". Like the bumps and grooves are all the same. Think like a valet key that the old hondas used to have. The key looks identical, yet, it will only open certain things, I have no idea how this is possible, unless it is chips/computers.
Quote:
Originally Posted by cebuan
A mechanical key has long grooves in the sides, which enable it to slide into a lock, and teeth in one edge which enable it to be turned against the position of tumblers inside the lock. If the key fits into the slot and then turns the lock when you get it in there, it has worked and unlocked the mechanical assembly. Whether or not there are electronic components depends on chips embedded in the system.
When a key fits perfectly but still won't turn, it must be electronic. The car must somehow know that the key is not correct, this is what has me so confused.
Quote:
Originally Posted by M3 Mitch
Your question does not involve the chip keys of more recent cars so I'll ignore the chips and talk about old school keys that are strictly mechanical:
You are talking about keys having the same "warding" but not the same "cut". The "warding" is the set of grooves in the sides of the key, that determine if a particular key will enter a particular lock.
The "cut" is the set of ridges on the edge of the key, that position the tumblers at the correct depth so the cylinder will rotate.
I believe the cars I've tried this on are considered modern and have chips in the keys. Based on your definitions, these keys have the same warding and cut. I have tested this on 98-02 Accords, 97-01 and 02-06 Camrys, and 010-012 Fusions. The Keys look completely identical, and fit perfectly into the ignition and door/truck locks, but still won't turn. This has to be computerized. I just wonder how it works. Thank you all for your help though, in trying to explain to this moron (me) how these engineers figure this stuff out.
My Porsche has a valet key. While it looks similar to the real key, it's not exact... it's slightly shorter. It works in the ignition only, and will not unlock the glove box or center console.
Our other cars... I don't know actually. We have their "enter and drive" option where the door senses the key as you approach and unlocks the door, and we just push a button to start the car, so we never even have to touch the key. There is an actual key inside the keyfob, to be used when the battery is dead, but we've never had to use it.
The keys I'm thinking of have the exact same "look". Like the bumps and grooves are all the same. Think like a valet key that the old hondas used to have. The key looks identical, yet, it will only open certain things, I have no idea how this is possible, unless it is chips/computers.
When a key fits perfectly but still won't turn, it must be electronic. The car must somehow know that the key is not correct, this is what has me so confused.
I believe the cars I've tried this on are considered modern and have chips in the keys. Based on your definitions, these keys have the same warding and cut. I have tested this on 98-02 Accords, 97-01 and 02-06 Camrys, and 010-012 Fusions. The Keys look completely identical, and fit perfectly into the ignition and door/truck locks, but still won't turn. This has to be computerized. I just wonder how it works. Thank you all for your help though, in trying to explain to this moron (me) how these engineers figure this stuff out.
The locks are just mechanical. Computer is not preventing them from turning. They're just not actually identical despite appearing so at a glance.
This reminds me of the time I was out shopping, headed back to the car, inserted my key.... it went it but didn't open the door (I don't have electronic locks or anything - Duh...... the same color Corolla was parked next to mine and I obviously wasn't paying attention - so there is obviously some diff. as the key did fit the lock just didn't do anything from there.
When a key fits perfectly but still won't turn, it must be electronic. The car must somehow know that the key is not correct, this is what has me so confused.
Half the keys I buy at Walmat fit perfectly but still won't turn and I have to take them back and have them recut. If the keymaker starts with the correct blank, it will fit into the keyhole straight off the rack. It's the tooth cut that enables it to turn, according to the position of the tumblers lin the lock.
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- Duh...... the same color Corolla was parked next to mine and I obviously wasn't paying attention - so there is obviously some diff. as the key did fit the lock just didn't do anything from there.
