VATS

Vehilcle Anti Theft System

On the newer GM cars there is a built in anti theft system that disables the fuel injectors until the correct key is inserted into the ignition. Once the correct key is recognized, a signal is sent to the ECM allowing the injectors to fire. I could have had my computer reprogrammed to delete this, but I decided to retain this built in security feature. Even when hotwired, the car will start and die approximately 2 seconds later making it impossible to drive.

In order to convince the computer that I was not trying to steal the car, I needed to come up with a 5V 50Hz signal generator to create the correct signal. The device is small enough to fit im my pocket so whenever I leave the car somewhere, I just unplug it and walk away.

Below is a schematic of the circuit as well as a description on how to build it.

First you will need the following parts:

555 timer
a small pc board
3.3K resistor
2.2K resistor
10K resistor
100 Ohm resistor
two 0.1uF ceramic capacitors
1 uF electrolitic capacitor
12V Zener diode
small plastic enclosure
three pin connector

Connect one of the 0.1 uF capacitors between pins 1 and 8. Connect the 12V Zener diode between pins 1 and 8 with the banded (+) end to 8. This is to absorb voltage spikes caused by the starter. Also to pin 8 connect one end of the 100 Ohm resistor. The other end will be connected to an ignition hot source.

Connect pin 4 to 8 and pin 6 to 2.

Connect the 3.3K resistor between pins 7 and 8.

Connect the 2.2K resistor and the 10K resistor between pins 6 and 7 in series.

Connect the electrolitic 1uF capacitor + side to pin 6 and - side to pin 1.

Connect the other 0.1uF capacitor between pins 5 and 1.

Pin 8 is ground.

Pin 3 is output and can be connected to the ECM.

Install

	VATS Vehilcle Anti Theft System On the newer GM cars there is a built in anti theft system that disables the fuel injectors until the correct key is inserted into the ignition. Once the correct key is recognized, a signal is sent to the ECM allowing the injectors to fire. I could have had my computer reprogrammed to delete this, but I decided to retain this built in security feature. Even when hotwired, the car will start and die approximately 2 seconds later making it impossible to drive. In order to convince the computer that I was not trying to steal the car, I needed to come up with a 5V 50Hz signal generator to create the correct signal. The device is small enough to fit im my pocket so whenever I leave the car somewhere, I just unplug it and walk away.
	Below is a schematic of the circuit as well as a description on how to build it. First you will need the following parts: 555 timer a small pc board 3.3K resistor 2.2K resistor 10K resistor 100 Ohm resistor two 0.1uF ceramic capacitors 1 uF electrolitic capacitor 12V Zener diode small plastic enclosure three pin connector
	Connect one of the 0.1 uF capacitors between pins 1 and 8. Connect the 12V Zener diode between pins 1 and 8 with the banded (+) end to 8. This is to absorb voltage spikes caused by the starter. Also to pin 8 connect one end of the 100 Ohm resistor. The other end will be connected to an ignition hot source. Connect pin 4 to 8 and pin 6 to 2. Connect the 3.3K resistor between pins 7 and 8. Connect the 2.2K resistor and the 10K resistor between pins 6 and 7 in series. Connect the electrolitic 1uF capacitor + side to pin 6 and - side to pin 1. Connect the other 0.1uF capacitor between pins 5 and 1. Pin 8 is ground. Pin 3 is output and can be connected to the ECM.




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