Disable VATS

[Terry Martin]

Joe Boucher wrote:
>> My friend would like to part the car out.  Before he pulls
> >>the engine he would like to video tape the motor running, but he doesn't
> >>know if their is an easy way to bypass the VATS. Any susgestions?

> >The cheapest way is get a 555 timer and clock it at a 50% duty cycle for
> >the PCM VATS terminal to ground.
> 
> The following quote is from the description of how a person stuffed a '94
> 3800 into a Fiero:
> 
> Pass Key theft deterrent must be by-passed. I had the ignition key and
> could therefore measure the resistance of the pellet. A
> 10 turn pot was matched to this and soldered to the inputs of the stock
> Pass Key module which will feed a 50 hz "ok" signal to
> the PCM. A more elegant solution of a 50 hz wave generator is suggested but
> mine works.
> 
> Tom explaination is a bit above me.  I know what a 555 chip is but I don't
> know how to do what he suggested.  Could you get a variable resistor, hook
> a digital voltmeter to the output of the VATS and change the resitance with
> the potentiometer till you get an output from the VATS?  That would give
> the resistance you need.
> 
> A brute force method but it might work.

Nope, unless you have the VATS "R" (read ohm) table, which is easy
enough to get. VATS works because if you put any resistance across the
ignition loop that does not almost exactly match the "burned in" value,
it goes into a four minute (or so) time out period in which nothing will
work, including the right one. If you jump in before the time out period
has reset, it goes back to the beginning, and you could potentially (pun
intended be there forever.

A simple timer circuit using a 555 timer probably comes in the package
if you buy it at an over the couter retailer. Other than that the local
library will have it in one book or another. That you can use a trim
pot. to set the frequency, and because the VATS control module is not in
the loop it won't mess with your rig. 

Don't bother trying to rip off a car this way, you'll get your ass
caught, and you have to disconnect the VATS control anyhow which will
take the rest of your life.