Hi Guys!

Ok, so I have been all over the internet, especially thirdgen.org, looking for a solution to my problem. I have solved several issues only to arrive at a new and even more puzzling one. At the core of my troubles is the mystery and general lack of information surrounding the VATS system.

First off, a sitrep of the last few steps:
>Cranks at key, does not fire
>No fuel pressure at rail, no prime, plenty of fuel in tank
>Check all fuses at fuse block for continuity, replace inline F/P fuse
>Cranks at key, does not fire
>Jump ALDL connector port G
>Fuel pressure now at rail, good fuel pump
>Replaces fuel pump relay
>Cranks, does not fire, no injector pulse
>VATs Module? possible issues with power, ground or faulty?

Some useful diagrams:






Called the dealer service department to find out if I could just swap in another junkyard VATS Module. Both GM dealerships I called stated this was impossible. The first mentioned what I had feared: that the VATS module, as well as the Starting Enabler Relay, only function with their corresponding key blank. This makes sense to me, although it makes finding another VATS module a pain.

The second mentioned something seemingly impossible, that it was actually tied into the vin of the vehicle, meaning that even among identical key blanks they were not interchangeable. He also mentioned that they had the ability to store states, such as ‘failed enabled’ and ‘failed disabled’. The Idea that it's somehow tied to the vin seems ludicrous because it would have to be stored in the ecm, and we know ecm’s are interchangeable without creating VATS issue. Similarly, I don't see how a VATs module could possibly store states if the battery has been disconnected. This is 1980s technology and it is most likely functioning on some rudimentary ram, which is cleared when battery or ground are removed.

Furthermore, this article makes no mention of these capabilities when discussing the VATS system:

http://www.lockmasters.com/ecommerce...%20Article.pdf





Any help or information is appreciated
Really want to get her back on the road!

 

This vintage VATS does not store vehicle specific information. The VIN is irrelevant. What is important is that any key blank used must have the correct pellet resistance to match the VATS module. GM used 15 different resistances, and dropped one early on in the program so that practically only 14 were used. Thus, any key cut to fit the lock cylinder and containing a pellet of the correct resistance will work.

However, this may not be your problem at all. If operating properly, the VATS module sill not even allow the starter to operate if the module does not recognize the key resistance. It is more likely that the ECM is not seeing distributor reference pulses when the engine is cranking. This will prevent the fuel pump from running, prevent injector pulses, and may be the reason there is no ignition (spark).

 

Usually the best approach is to eliminate the key from the system. Assuming it's the same as the 89 year cars. Measure the resistance of the key pellet, cut the wires from the column and put a standard resistor in the circuit. A new Vats module, from what I've read, has no stored code, has to be used with a key to have it put in memory. New module and a standard (no pellet) key and it's good to go. If you can still get a new module? Then there's a circuit board you can build that will send the pulsed ground signal to the ECM in place of the VATS module, eliminate it completely. Pretty simple circuit with a 555 IC timer. Google for this, seems like it was on a Fiero forum.

 

I had the issue of VATS recognizing my key. I think there is a short in a wire between the key and the module. Sometimes it would start other times it wouldn't. I wired in a resistor that matched my key and now I don't have any issue. Its a pretty easy thing to try if you wanted to eliminate that as the issue. I may look into the circuit board now, sounds like a better solution, but the resistor trick has worked great for a long time.

 

Here's your chart if needed in the future