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VATS Bypass


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.


So How Do I Bypass It?
There are 3 ways that I know of:
1. Remove the VATS module.
2. Ground the White/Black wire underneath the dash.
3. Create a 'Resistor Plug'.

1 Explained - To sucessfully remove the VATS module, you'll need to 'burn' an ECM chip with the VATS feature disabled, and create a 50Hz square wave signal emitter. I DO NOT know how to make this device. I have not investigated it. You'll also need to ground the Black/Yellow wire going to the starter relay. The VATS module is located behind the RH side of the instrument panel.

2 Explained - You'll need to cut and splice a new wire into the White/Black wire underneath the dash. Then ground the new wire to a reliable source. I have heard this works but HAVE NOT tried it. You can also wire it to a hidden switch to regain the security you once had.

3 Explained - Under the dash, near the Yellow SIR(airbag) connector, is a 2 wire connector. The black wires go to the lock cylinder. The White/Black wire and the Purple/White wire goes to the VATS module. The White/Black wire and the Purple/White wire connector is a female end. You'll need to go to a junkyard, or somewhere with electrical connectors, and cut out a male end of the same type of connector. Leave about 3 inches of wire on it. Once you have the connector, figure out your key pellet resistance. Go to an electronics store and buy a resistor that's exactly the same resistance or close to it. Soder in the resistor to one end of the connector. If you have any heatshrink, cut some off and put it on now. Then, soder in the other side of the resistor and shrink the heat shrink over the assembly. Plug your 'Resistor Plug' in place of the lock cylinder wires and your done.


What Are The Benefits And Disadvantages Of Each?
1. The removal will take most of the day, if not more. Once out, it can not be easily replaced. It will save you the trouble of having the module itself go bad. And, if you're a serious racer, you'll save weight.

2. Cutting and splicing the original wiring can be annoying, especially if your splice comes undone in the middle of nowhere. It is fairly simple to do and does not require any special resistors or connectors.

3. This is the ideal setup for someone who wants to keep their car intact as mach as possible. This mod can be undone in a minute and you can even wire in a switch if you want.




EDIT: I found out that the VATS module does not just ground the dark blue wire going to the ECM, it sends a 50Hz square wave signal to the ECM.



Written by Chris Wilson. AKA 92RSB4C Contact Me
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