If there is a problem with the vats module,the car will not crank? I've been having a problem with no start,changed the starter,checked everything thing else.Thing is,when it will not crank,the security light on the dash stays lit whenever this happens,this leads me to believe that it is a vats problem.Any one have this problem?,and where is the vats module,wiring etc.........?

It most likely is not the module, but the wires from the ignition cylinder. If you want to bypass the VATS system, do a search for "VATS bypass" for the procedures.

I was running into the same problem. The VATs does 2 things, disables the started & does not pulse the injectors. It's a little hard to test because the VAT's sends a squre wave to the ECM on a blue wire, (can't reproduce it). I jumpered my started to make it crank, then checked to see if I was getting pulses on the injectors. I have a 91 GM manual with all the info, so let me know if I can help.

When the SECOND $210 VATS module c-----d out, I decided to be
rid of it altogether. As an alternative to programming it out of the
ECM, board member S10Wildside (also an e-bay power seller) builds
the square wave emulator for $15 plus shipping.