GM ECM: Vats

[George M. Dailey]

At 09:11 AM 6/11/96 -0700, you wrote:
(snip)  A description of the (VATS) system is in order.
>>First off gm has a resistor embedded in their keys. 

     TRUE

This can
>>have one of 15 resistance values. When five volts is 
>>applied to that resistor one of fifteen voltage values results

I beg to differ my good man. While installing the '89 350 TPI into my '58, I
had to crack the VATS enigma.  What I found out was that the resistor in the
key provided a voltage to the VATS module. The VATS module would then send
about a 30hz signal to the ecm to say "a-okay". The ecm would then allow the
injectors to fire. 

I built my VATs defeater from a 555 timer. Configured it to go +5v to
groung.  The ECM will provide the +5v, you just need to ground it at about
30hz. 

>>The older ones
>>used a separate VATS module which makes life easier.

No info on the newer units. I was told they use a 40hz signal with a module.


Good luck, and keep us informed.

GMD