Originally Posted by disgruntled
I think that there is a way to program the key with a good one as well, but don't hold me to that. I also know that if you happen to have a Home Depot in your area, they will sell you the blank, cut the key, and then program it also for $60 bucks. The price isn't great, but it's much better than sending your only good key to who knows where to get it cut and programmed, or paying the dealership prices. Good luck.
The transponder inside a car key has a fixed reply that it transmits back to the car when querried. When you "program a key" you are actually doing nothing to the key, but you are telling the car to accept the reply it gets from that transponder key as a valid reply. Nothing actually happens to the key itself. Because of this, it is impossible for Home Depot to actually "program a key" unless they have some special hardware that will rewrite the internals of a key to reply differently. Since the transponder chip is programmed before it is put into the keys, I don't think Home Depot has that technology to do that (sorry Home Depot). Home Depot sells only Non-transponder type car keys (dumb keys). Great for unlocking trunks and doors, and turning on the accessories, but not for starting the car. Maybe they are starting to carry electronic house keys, so maybe that is what they told you about.
They also cannot program the car to accept a second key without having the car and a programming computer (Dealer or Locksmith item costing several thousand dollars) since the programming takes place on the car not the key.
When the dealer or locksmith programs your car to accept a second key with the computer (when you have none or only 1 available), there is a delay imposed by the car computer (I think it is 10 - 15 minutes depending on the vechicle). This LONG delay supposedly stops someone from making a physical copy of your key and then quickly programming it into your car to get a working copy of your ignition key (possibly without your knowledge). I guess they feel if you already have 2 working keys in your posession you must be the owner, so it's OK to accept another key code more quickly. You can program a third key (up to 5 total) yourself, if you have 2 already programmed keys. The exact procedure varies between car companies, models and model years, but the general procedure goes like this...
1) Have 2 working keys, and close all doors (some models).
2) Insert key A into the ignition
3) Turn ignition to the ON position (don't start the car) and wait for some amount of time (normally 1 - 5 seconds or so).
4) Turn the ignition back to the OFF position and wait for some amount of time (again, normally 1 - 5 seconds or so).
5) Possibly repeat step 3 and 4 up to 4 more times (depending on model).
6) Remove key A and insert Key B into the ignition.
7) Repeat steps 3,4 and 5 with key B.
8) Remove key B and insert the unprogrammed Key C and turn the ignition to ON (again don't start the car yet).
9) Wait for some amount of time
10) On some models start the car with new key C, but doing this on some others will terminate the programming sequence a this key.
10) If a Key D (or E) is required , repeat steps 8, 9 and 10 with Key D (or E).
If you already have 3 keys programmed, and you try to program 3 more, the key that was used longest ago will be removed and replaced by the last key programmed.
Hopefully this will help everyone.