Bypass VATs on 92-99 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat

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Old 01-19-2009, 03:14 PM   #1
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Default Bypass VATs on 92-99

92-95 if the car cranks, vats is not the issue
96-99 if the car does not crank, vats is not the issue.

If you have a VATs on your car, your key will look something like this. The small black oval on the metal part is the VATs chip

This will only bypass the chip on your key, it will not disable the VATs.

Before bypassing your VATs please read below.
-- When you insert your ignition key and attempt to start the car, will the car not even attempt to crank over? Does the "Security" light flash during any time you're attempting to start the car?
The simple solution is to first clean off the chip on your key or try another key for the same car. If that also doesn't work, then follow these instructions for a fast, simple, and relatively inexpensive repair.
**NOTE** After performing the following procedure, your vehicle'* factory starter interrupter (VATS) will be disabled. A thief will be able to steal your car much easier than if the VATS system were enabled.
Any changes made to your VATs is your choice, the author, owner, or operators of this site may not be held responsible for damage or theft of your car.

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. But because of the popularity of calling it a computer chip key, so will we. So that we don’t confuse. The black chip on the blade of the key, is actually a resistor. GM first started using the Vats key in 1986 on the Corvettes, then some of the Cadillacs, etc. GM uses 15 different resistors in their VATS keys. Just by looking at the keys you can’t tell the difference.

How does the VATS System work?

Each VATS key has it’* 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, along 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 the 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 change anything to tell you. There is another way for you to read the key value yourself. If you have a Volt Meter you can test the OHMS (resistance value) of the chip yourself. Just set your Volt meter to check 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 volt meter 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.
This chart is for any GM product, Buick, Cadillac, Oldsmobile, Chevrolet, and Pontiac that has a VATS key (single or double-sided.)

VATS # (K)OHMS (Set your meter to the 20k ohm setting)

1———— 0.402
2———— 0.523
3———— 0.681

Tools and supplies needed:
Soldering Iron
Wire Cutters/Strippers/Crimper
Voltmeter/Ohmmeter (DMM)
Approx. 8 inches of 16 ga. wire (speaker wire works great)
"Bullet-Style" crimp on connectors
Heat Shrink Tubing
Resistors of varying values (totaling the resistance measured across the key'* "pellet")

1. Take your DMM, set it to measure Ohms (use the 20k setting.) Measure the resistance across the pellet of the ignition key. Place one probe on the silver part of one side of the pellet, and the other probe on the other side. Write this value down.

2. Purchase a resistor or resistors that add up to the value measured in step 1. Radio Shack is a great place to go for the resistors, heat shrink tubing, and the "bullet-style" crimp on connectors.

3. Take the 16 ga. wire and cut into 2 four-inch pieces.

4. Strip off approx 1/16" of insulation off each side of both wire pieces.

5. Put your resistors together in series (or if you're lucky and have a chip that has a resistance that matches a single resistor) and solder one wire to one end of the resistor(*) and the other wire to the other side.
Example: You measure 11.72 on the 20k (k meaning kilo or 1,000) scale. The closest match is 11.801 which is a #15 "chip." Always remember that resistors have a tolerance of 2%, meaning the resistance value of the "pellet" can be either 2% higher or 2% lower than 11.801 k ohms (11.72 falls in tolerance range.) You will want to aim for 11,801 ohms. So when you go to Radio Shack you want to pick up a 10,000 ohm (10k,) a 1,000 ohm (1k,) and an 800 ohm resistors to wire together in series to achieve the 11.801k ohm value.
Here'* an example of how you'd connect the above mentioned resistors in "series"

wire------10k ohm------I------1k ohm------I------800 ohm------wire

6. Measure the resistance across the 2 wires now that the resistors are soldered to them. Be absolutely sure the value matches that of the resistor pellet in the ignition key (within 2% up or down.)

7. Cut a length of heat-shrink tubing to cover up the resistors, allowing a small bit to hang over onto each of the 2 wires. Use a lighter or heat gun to shrink the tubing.

8. On one of the wires, crimp on a male bullet connector, and on the other wire crimp on a female bullet connector.

9. Now move to the car. Remove the under-dash kick panel.

10. Look for an orange wire running down the steering column. This wire should have a "rubbery" feel to it, and it is the only orange wire running from the column.

**WARNING** Do not tamper with any of the wires near the column wrapped in yellow harness tape or any yellow wire. These wires are for the airbag. Tampering with any of these wires could result in the airbag discharging.

11. Cut this wire (there are 2 small wires inside) and strip back the insulation on the wires on the opposite side of the steering column.

12. Install a male bullet connector to one of the 2 wires, and a female on the other.

13. Plug in your "resistor pack" that you made by mating the male and female bullet connectors.

14. Attempt to start the car. If your problem was with the VATS reader in the ignition lock cylinder, this will start the car.

If this won't start the car, then the problem is in the VATS module. If the VATS module is bad, remove the resistor pack. Strip the insulation off the other side of the main wire cut (running from the column) and place a male connector on one wire and a female on the other. Plug the 2 halves back together to restore the function of the VATS reader.

Last edited by Danthurs; 01-19-2009 at 03:21 PM.
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