Quote from some page.
immobilizer bypass, bypass kit technology:
A
transponder bypass (
immobilizer bypass,
bypass kit, databus bypass) is a pretty simple idea. Some different techniques are involved, depending on who's product you are using, but the idea is the same. Put a working, programmed transponder key in the vehicle, and you can use an auto starter for example.
The problem of course is that you render that wonderful transponder protected ignition redundent. You now have nothing better than a plain ignition switch protecting your car. In many cases, these ignitions can be picked or bypassed in a matter of moments by a pro.
You better have them wire up your cutoff switch to the auto starter, because without fuel the starter is kinda pointless.
I know of vehicles that have been stolen right from peoples parking lots and driveways while the eat diner. Being near to your car is no guarantee of security.
One guy I met had his truck stolen while he was in a coffee shop. When he called the insurance company, they asked him if he had an auto starter. They couldn't NOT pay him, because the theives still had to pick the lock, because he took his keys with him. Still, it shows you just how fast you can lose a vehicle.