http://www.gmforum.com/showthread.php?t=279119What is VATs?
Vats stands for Vehicle Anti Theft System. Lots of people refer to this type of key, as a " computer Chip key". This key or "Chip" has nothing to do with a computer, nor is it a chip. But because of the popularity of calling it a computer chip key, so will we. So that we don’t confuse. The black chip on the blade of the key, is actually a resistor. GM first started using the Vats key in 1986 on the Corvettes, then some of the Cadillacs, etc. GM uses 15 different resistors in their VATS keys. Just by looking at the keys you can’t tell the difference.
How does the VATS System work?
Each VATS key has it’s own unique cuts on the key to operate the lock. but the cuts alone will not allow the car to crank. This is called a mechanical key. Each car has a VATS module (Brain) under the dash that communicates to the starter, fuel pump, and the ignition lock. Each VATS module is randomly given a # (value) from the manufacturer. When the proper mechanical keys, along with the proper VATS chip (resistor value) turns the ignition lock, the VATS module reads the chip on the key . If it is the correct chip, the VATS module will tell the starter and the fuel pump to operate. If the wrong chip is read, the VATS module will tell the starter and the fuel pump to shut down.
How to determine the Value of your key:
By chance you may know what VATS key you now have. Most people do not. There are basically two ways to determine what VATS key you have. Remember, there are 15 different possibilities. First, your key can be "read" in a VATS tester. Most locksmiths have these readers, and don’t change anything to tell you. There is another way for you to read the key value yourself. If you have a Volt Meter you can test the OHMS (resistance value) of the chip yourself. Just set your Volt meter to check OHMS, take each lead and place it on each side of the "chip" on your key. A number will appear. Take that number on your volt meter and apply it to the OHMS chart below. Keep in mind that it may not be exact. Just pick the closest value to your reading.
This chart is for any GM product, Buick, Cadillac, Oldsmobile, Chevrolet, and Pontiac that has a VATS key (single or double-sided.)
VATS # (K)OHMS (Set your meter to the 20k ohm setting)