I bought a 2002 Jetta TDI a few months ago. Wonderful car, enjoy driving it, but only have a valet key for it, the master key was NOT available. I've thought about getting a second key made, just in case, but am a bit confused by the transponder system.
From my reading, there's a chip in each key, and the code on the chip is read by the car using a coil in the steering column. To unlock the steering and start the car, you need a key that has been cut to match the car. To keep the engine running, you need the chip to be recognized by the cars computer system.
I've seen blank keys available for less than $50, and apparently they can be cut to match the car by providing the VIN and/or photos of an existing key, so getting a physical key doesn't seem to be too much of a problem.
Getting the new key code into the computer apparently requires a dealer or locksmith, so that's an extra expense.
First question: What happens if the car battery runs down or has to be disconnected to service the engine or to replace the battery? Does the computer lose all the codes? That would make the car inoperable and probably require a tow to a dealer! Seems unlikely, but.....
Second question: If I get a new key cut, but NOT programmed into the car, it could still be used to unlock the door and to work the ignition switch. If my current key was close to the steering column (but not in the switch), would that allow the car to start and run? In other words, how close to the steering column does the coded key need to be to be read?
third question: Relay 109 seems to be the main ON/OFF control for just about everything that makes the engine run... If I used a non-programmed key to unlock the door and to work the ignition switch, would bypassing the relay contacts with a switch allow the engine to run? I'd have to turn the switch off to kill the engine, but that would be a small price to pay if it would defeat all the programming nonsense!....
