Go onto fleebay. Look up VATS KEYS in the fleebay motors section. Go for almost ANY VATS key and select it with your mouse. Almost every vendor selling blank VATS keys has the chart from #1 to #15. I used a DVM (actually a Digital Volt OHM meter) and just put one probe on each side of the pellet and read out the resistance. The charts on fleebay also tell you the allowable tolerances. My Corvette is like one ohm away from the specified value on the chart while the Cadillac is about 80 ohms away but still well within the acceptable range.
If you don't have a decent ohm meter you can get one from Harbor Freight for a few bucks.
The diagrams you made are CORRECT the resistors are in SERIES so that the total resistance should add up to the resistances of each resistor in the chain. I don't think it matters where the resistors are as long as they actually go across the place where the computer expects to see the pellet. There are some resistor VATS bypasses also on fleebay but I don't recall how much they want for a few resistors.BIGHNAK

 

Well, the car won't start at all and is stuck at a friend's house. I tried making a new by pass with one of those adjustable resistors. Still didn't work. I bought a new VATS module, hopefully it works. The other day, it took over 2 hours to get the car to start. I hear the fuel pump, the secruity light is on, and the starter does nothing then I get the message starting due to theft system. If the module doesn't work I'll just get the car towed some where to get it fix. I'm not taking it to a stealership.

 

FINALLY!!! I FIXED IT! I got the new VATS module and it said after you hook it up, turn on ign. for 5 seconds to program it. So I unhooked the 2 wires going to the ign. and put in my adjustable resistor thing and put it to what I think the key is. Turned the ign. on for able 10 seconds to make sure it is programed. Turned it off and tried starting it and it started. I turned it off for awhile then tried again and it still worked. I can actually leave the house now.

 

Now you can post an add on fleebay as an official VATS fixer. Where did you get the info to program the system by turning ignition on for 10 seconds? BIGHANK

 

I bought a new VATS module of a GM parts website and the instrutions were inside the box when I opened it.

 

Pass key module comes not programmed. When installed pellet resistor value burns in permanently in to module when key is turned to run. Module can be reprogrammed.

 

slowroll, robotic_junky

I would like to make this a crystal clear diagnosis and solution.

I see this type of problem a whole lot, specially in the Allante Community where after 15 years of using the car, the general belief is " when not If " .. it seems that the "chip" is the most likely candidate to fail (better have a good and tested spare key), followed by the wires between the ignition cylinder and the module. Many an Allante owner will carry a bypass kit to install upon a failure. The wire breaking in the Allante become so common, that there is someone in the Allante club specifically assigned to make the kits for members.

What I understand from all of this:

- the module had failed.
- the new module self programs itself to the key in place by being on for 5 seconds.
- in this particular fix, used the bypass to program the module where one would nornally use the key.

Is that about right ?


=======================


I also understand that the same VATS keys are used on the following Cadillac models - the following info was gathered from sellers of the aftermarket sellers of VATS keys. Going price, out the door from around $18 to $30 for the set.

[IMG]local://upfiles/2893/662F9AE3F67D4747A5E1BECB74A4B525.jpg[/IMG]

Cadillac Allante 1989 1990 1991 1992 1993
Cadillac Brougham 1992 1993 1994 1995 1996
Cadillac Concours 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999
Cadillac DeVille 1991 1992 1993 1994 1995 1996 1997 1998 1999
Cadillac Eldorado 1989 1990 1991 1992 1993 1994 1995 1996
Cadillac Fleetwood 1992 1993 1994 1995 1996
Cadillac Seville 1989 1990 1991 1992 1993 1994 1995 1996


VATS # K OHMS
1———— 0.402 (acceptable range .386-.438)
2———— 0.523 (acceptable range .502-.564)
3———— 0.681 (acceptable range .650-.728)
4————-0.887(acceptable range .850-.942)
5————-1.130 (acceptable range 1.085-1.195)
6————-1.470(acceptable range 1.411-1.549)
7————-1.870(acceptable range 1.795-1.965)
8————-2.370(acceptable range 2.275-2.485)
9————-3.010 (acceptable range 2.890-3.150)
10————3.740(acceptable range 3.590-3.910)
11————4.750(acceptable range 4.560-4.960)
12————6.040(acceptable range 5.798-6.302)
13————7.500(acceptable range 7.200-7.820)
14————9.530(acceptable range 9.149-9.931)
15————11.801 (acceptable range 11.320-12.290)

WHAT IS VATS?
Vats stands for Vehicle Anti Theft System. Lots of people refer to this type of key, as a " computer Chip key". This key or "Chip" has nothing to do with a computer, nor is it a chip. The black chip on the blade of the key is actually a resister. GM first started using the Vats key in 1986 on the Corvettes, then the Allante, ECT. GM uses 15 different resistors in their vats keys.

How does the Vats System work?
Each vats key has it’s own unique cuts on the key to operate the lock. But the cuts alone will not allow the car to crank. This is called a mechanical key. Each car has a Vats module (Brain) under the dash that communicates to the starter, fuel pump, and the ignition lock. Each vats module is randomly given a # (value) from the manufacturer. When the proper mechanical keys, with the proper vats chip (resistor value) turns the ignition lock, the vats module reads the chip on the key. If it is the correct chip, the vats module will tell the starter and the fuel pump to operate. If the wrong chip is read, the vats module will tell starter and the fuel pump to shut down.

How to determine the Value of your key?
By chance you may know what vats key you now have. Most people do not. There are basically two ways to determine what vats key you have. Remember, there are 15 different possibilities. First, your key can be " read " in a vats tester. Most locksmiths have these readers, and don’t charge anything to tell you.
There is a way for you to read the key value yourself. If you have a Volt Meter you can test the OHMS (The Value) of the chip yourself. Just set your Voltmeter to check to 20 K OHMS Take each lead and place it on each side of the " chip " on your key. A number will appear. Take that number on your voltmeter and apply it to the OHMS chart below. Keep in mind that it may not be exact. Just pick the closest value to your reading.

 

I´m having the same problem down here at Puerto Rico with my car. I have not been able to find a Passkey Module in a reasonable price.(Dealer sells it to me for 500+tax) Please can some one help me in this one......
STS 94