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Member
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Join Date: Dec 2004
Location: Seattle
Posts: 230
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Member
Join Date: Dec 2004
Location: Seattle
Posts: 230
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Why programming a key clears yaw/decel memory
Many (including me) frequenty talk about "programming a new key" for the 4runner and other vehicles with immobilizer or alarm-equipment that makes use of a chip in the ignition key.
The chip in the key is actually a small device that responds to a radio frequency stimulus signal from the vehicle (a transmitter in or very near to the ignition switch) and replies with a digital code unique to that key.
So when you're programming a new key, what you're actually doing is programming the vehicle's own main computer or security module computer (and not the key itself) to accept a specific key. The key itself is unaffected. This process is sometimes called "enrolling the key" and the same thing could happen with a lock/unlock key fob, etc. It's pretty similar to setting up a garage door opener with "rolling code" technology to accept additional remotes.
One thing to keep in mind is that to do the enrolling of a new key you need one of Toyota's "hand-held tester" units and a valid master key for the vehicle in question. They're the black-bodied keys and not the gray valet key. If you lose both master keys you can still use the valet key to open and operate the vehicle, but to get a new key made you (actually the dealer) will have to buy a new security module (several hundred dollars I think) and enroll new key(s) to that module. That's the way they do the ignition immobilizer security, and keep thieves from programming their own keys as a way to steal your car. The lesson here is that if you lose one master key you might consider getting a replacement soon, because if you lose the other master you're in for a bigger bill.
Of course this info is current for the 4th gen 4runners that I'm familiar with. Things can always change.
It's kind of a pain, but I hear from local police that these chip-equipped keys and associated immobilizers are successful at reducing the theft rate of these vehicles. Now if Toyota would only make a more effective lock for the spare tire...
Last edited by MicaBlue03; 01-17-2010 at 02:57 PM.
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