When you turn the ignition key on your General Motors equipped vehicle anti-theft system (VATS), a resistance is sent to a module through your car or truck’s wiring, and based on the expected result one of three things can happen: tamper, normal, or fail enable mode. Let’s take a look at what’s going on in when these things happen.
If everything goes well with your key, ignition switch, wiring, and VATS module, the expected resistance value will be seen and the module will allow the start enable relay and send a fuel enable signal to the computer (ECM), turning on the injectors. Supposedly this fuel enable signal is pulse width modulated, which is a fancy way of saying that the signal is rapidly switched on and off in a pattern that would be difficult to duplicate. From there, your car starts like normal.
If the expected resistance is not seen by the VAS module, your car’s security light will come on for approximately four (4) minutes and during that time your car will not start up. Neither the fuel enable signal nor the starter relay will be enabled. The value that’s expected is what was sent the last time the anti-theft system was reset/reprogrammed, which you can do yourself (just follow the link). Of course, if there’s some other problem causing your resistance to drift out of range or your module to not be able to properly send signals to your ECM, you’ve got another problem on your hands. Consider bypassing at this point.
Fail Enable Mode
This mode is intended to keep you from getting stranded when you’ve got the right key in your hand. If a failure is detected sometime after the car is started, while the key is in the ignition, it’ll trip the security light but still allow the car to be restarted. If this happened to you, consider yourself lucky – you won’t be stranded. Oddly enough, however, it also allows the car to be started without a key, which is pretty darn stupid.
Bypass The Entire VATS PassKey and PassLock System
- Databus All Combo Bypass and Door Lock Module
- Covers over 95% of cars on the road today
- Supports legacy systems like VATS and PASSLOCK
- Supports doorlocks and override on cars like Toyota with pushstart ignition systems and Chrysler with electronic ignition
If you’re having problems getting stuck in tamper or fail enable mode (your vehicle is not starting due to the security light flashing), you have three choices: reset, bypass, or send it to the dealership to be repaired. Take it from someone who spent several weeks trying to fix it himself, broke down and sent it to the dealer for a week and spent another $180 and it wasn’t fixed, and finally just bypass the darn thing .