How do i bypass the vats system on a 91 firebird without resistors or a bypass module?

http://chickenroadlabs.com/2013/08/29/bypassing-gm-passlock-ii-vehicle-immobilizer

The security light would come on after making an attempt to start it.
The weak link in the VATS is the ignition lock. It has two small wires and they move when ever the lock cylinder is turned (to on or start...).

You can see where the wires break,


If you have a multi meter you can test it without taking much apart.
Measure the resistance of the chip in the key (touch a test lead to each of the sides of the chip)
Note the resistance.
Remove the trim panel under the drivers side of the dash.
Locate the wires and small black plug,


Unplug it and with the key in the ignition lock (does not need to be turned on or anything) measure the resistance between the two wires at the plug (the wires on the column side both white, black or yellow. Not the wires on the harness side).
The resistance should be the same or very, very close to the resistance of the key chip. If the resistance is too high or infinate then you have a break in those wires (note the top image).

You can cut the wires off the column, solder resistors that equal the keys chip (its actualy a resistor) to the wires and plug that back into the main harness. This is NOT a VATS bypass as many on the net believe. It simply bypasses the weak link, the lock cylinder. The VATS module is still in use. Though with this bypass, there is no security from the VATS (Vehicle Anti Theft System).
Or you can purchase a new lock cylinder. It will come with a key and you will then need to make a copy of the new key but with a blank that has the proper resistance.


If you do go with a new lock cylinder I also did a write up (with images) here not long ago for a person with another 89 that had a bad lock cylinder. You can search for that or let me know and I will write it up again.

Does that still have the old style key with the silver "chip" that can be seen in it? If so then this is very simple.
Its most likely not your VATS/Pass Key II module. The weak link in these systems is the lock cylinder. There are two wires that are connected when the key is inserted. But that "chip" is actually a resisistor. The two wires move when the key is turned and over time they will break.

There are modules to buy that can completely bypass the VATS system (a true bypass). They were made for engine swaps into vehicles that did not have the key and module or the resistance value was not known.

But since you have your key, a cheaper way to do this is to bypass the key's resistor and install your own.

You need a multi meter so you can measure the resistance of the key pelet. These are the values of the 15 different keys in the VATS.
1---- 0.402
2---- 0.523
3---- 0.681
4-----0.887
5-----1.130
6-----1.470
7-----1.870
8-----2.370
9-----3.010
10----3.740
11----4.750
12----6.040
13----7.500
14----9.530
15----11.801

Locate the orange wire harness. Its a thin harness that comes out of the column near your feet when sitting in the car and will have two small wires inside. Sometimes white, yellow or even black.
. With the key in the ignition lock (does not have to be on) you can measure the resistance between the two wires. It should read the same as the pelet in the key. If not then the wires are broke oe breaking.

If the resistance is not the same (or very, very close) cut off that plug and a length of the wire along with it.
Go to an electronics store and get a resistor or resistors that will total the same value as your key's pelet. The values can be off but not by much.
If more than one resistor is used attache them in series (one after the other) to the wires on the plug you cut off earlier, one end of the resistor to one wire and the other end of the resistor to the other wire. Solder them if you can.
Cover them with tape or heat shrink tube, plug it back in and try it out.

does your key have a black pellet at the base? if so try a new key! must have the pellet in it! if problem is still there after that! the ingition cylinder needs to be replace!

research vats bypass on google. I had to bypass, you simply measure the resistance through the chip, go to radioshack and buy the resistors that add to that amount or withing 2%. cut the orange wire that leads to the ignition and install the resistors bypassing the vats permanently.
http://vats.likeabigdog.com/
http://shbox.com/1/vats_bypass.jpg

there is a way I've seen it done but never have done it myself. That "chip" is like a resistor for the anti theft system. When I asked the guy how he bypasses it, he stated, "I find the correct resistance needed, then add a resistor in line so that it bypasses the ignition switch." This way the orginal keys will work even if they don't have the "chip." Now the vechile he did that on he still had the key with the chip. The chip or ignition cylinder wasn't contacting each other so it would sometimes run and sometimes wouldn't. So I don't know if he tested the key or if there is a different way. I know this isn't much help but I KNOW it can be done.

vats can be bypassed by locating wires from key lock cylinder under dash. this is common problem with this type of system. you must determine resistence valu of key resister and cut wires ind solder replacement to ends of wires that go to vats module which is seperate from ecm module.

It is located above th glove box you will need to take the upper dash pad off and the glove box asbly out and the module is attached to the dash reinforcement at the top of the glove box vats modules very rarely go bad it could be the ing lock cylinder ck for contanuity of the 2 wires at the bottom of the steering column in the orange insulation with the key in the lock cylinder and ohm meter across the 2 wires you should get an ohm reading then turn the lock cylinder and if the wiring goes to open the wires are broken and the lock cylinder needs to be replaced.

You cannot bypass GM Vag passkey. The key has a specific resistance the allows the BCM to start the car.

cant bypass if u want to get rid of it need to replace ignition system with a non security chip system--including computer reprogram