A colleague of mine sent me this, this may answer any future troubleshooter issues anyone may have with the VATS anti-theft system on the GM's.
What Is VATS And How Does It Work?
VATS stands for Vehicle Anti Theft System. It works by sensing resistance in the 'chip' in your key. The 'chip' is really a resistor pellot. The VATS module controls the starter enable relay and the fuel disable parameter in the ECM. If the wrong resistance is detected, then the VATS module will NOT let the ECM power the fuel pump. It also will NOT let the starter turn.
What Are The Resistance Values?
Your resistor value will be one of these 15:
1 - 402 Ohms
2 - 523 Ohms
3 - 681 Ohms
4 - 887 Ohms
5 - 1.13K Ohms
6 - 1.47K Ohms
7 - 1.87K Ohms
8 - 2.37K Ohms
9 - 3.01K Ohms
10 - 3.74K Ohms
11 - 4.75K Ohms
12 - 6.04K Ohms
13 - 7.50K Ohms
14 - 9.31K Ohms
15 - 11.8K Ohms
The only way to tell which one is yours is to check it with a meter.
What wires come out of the VATS module?
Orange - 12 Volts 10 Amps - Coming from the VATS fuse on the fuse block.
Black/White - Ground
Black/Yellow - Starter Enable Relay Control - Relay is located behind LH kick panel. Provides ground to relay.
Gray - Security Light - Provides ground to secuity light in instrument panel.
Pink/Black - 12 Volts 10 Amps - Coming from the ECM fuse on the fuse block.
Dark Blue - ECM Fuel Enable Control - Ground going to the ECM.
Purple/White - Resistor Pellot - Ground going to the lock cylinder.
White/Black - Resistor Pellot - X Ohms ground resistance going to the module coming from the lock cylinder.