C4 to C5 Corvette VATS Key Decoding Guide 1986 to 2004

This guide is designed to help you understand the VATS Key and determine which resistance value your Corvette’s Body Control Module will respond to. If at any time you have questions, please visit our Support section to open up a support ticket.

VATS Explained

The VATS acronym stands for Vehicle Anti-Theft System and is also known as the PASS-Key or Personal Automotive Security System.

Each VATS key has a resistor embedded in the key blade. Each resistor has 1 of 15 possible resistance values. The resistance value of a VATS key is called the VATS code. These resistors can also be referred to as resistor pellets, VATS Pellets or VATS Chips.

When this VATS key is inserted into the ignition lock, the resistor on the key blade touches two contacts inside the ignition lock. Once the resistor meets the contacts, the VATS system reads the resistance value of the inserted key. If the VATS key has the right resistance value, the car will start. If the wrong key is used and the wrong resistance value is read by the VATS, the Corvette will disable itself for FOUR minutes.

Before buying a new VATS key, you must know the VATS code which works with your Corvette.

Determining Your VATS Code

OPTION A: If you have a working VATS key…

You can determine the VATS code of your working key by decoding it. To properly decode the key, you will need an OHM meter.

NOTE: The resistor embedded in all VATS keys has metal prongs protruding out from both sides of the key blade. (See Figure 1) These metal prongs are used to touch two contacts inside the ignition lock which allows the VATS to measure the resistance value of the key.

If you have an OHM meter, follow the instructions below to decode your key.

1. Make sure your OHM Meter is set to 20k ?.
2. Place one lead of the OHM meter on the metal prong on one side of the key
3. Place the other lead of the OHM meter on the metal prong on the opposite side of the key.
4. A resistance value will be measured and displayed by the OHM meter. NOTE: To get an accurate reading, the OHM meter leads should only touch the key resistor’s metal prongs and not the key blade.
5. Use the chart below to convert the OHM meter’s resistance value to the proper VATS code.

NOTE: The resistance value measured by your OHM meter will likely not match the designed resistance value shown in the chart below. However, your resistance value should be a number that falls within the minimum and maximum resistance values in the chart (usually no more than a 3 to 5 percent difference). The closest resistance value in the chart to your measured value will correspond to the correct VATS code for your Corvette.

OPTION B: If you don’t have a working VATS key…

If you do not have a working VATS key, the Crew at Corvette Salvage has designed a detailed procedure which will help you identify your Corvette’s VATS Code.

Before starting the procedure, you will need to purchase the VATS Key Resistance Decoder Kit below. This kit includes the necessary resistors which will be used throughout the remainder of this guide.

Once you have the VATS Key Resistance Decoder Kit, follow the steps below:

• Disconnect the ignition cylinder wire that plugs into the dash harness at the base of the steering column. (See Figure 2) From this point on, we will ONLY be working with the dash harness plug. (NOTE: On a C4 Corvette, the ignition cylinder wire actually has two white wires running into an orange case.)

• After disconnecting, locate the two metal pins on the back side of the plastic dash harness plug. (See Figure 3) They may be very difficult to see without sufficient lighting. We have attached a picture to highlight the metal pins. You may need to bend the wires on the back of the plug to gain access to them.

• Take the resistor from the kit purchased above labeled #1 and bend the two metal ends to make a U shape with the two metal prongs sticking up.
• Use these two prongs and make them contact the two metal pins on the back side of the plastic dash harness plug. Make sure the metal prongs from resistor #1 stay touching the metal pins before proceeding to the next step. It is best practice to gently push the metal prongs as far into the back of the dash harness plug as possible. You want to guarantee that the metal prongs are touching the plug’s metal pins.

• With the resistor’s prongs touching the metal pins, use any key to try and start the Corvette.
• If the Corvette starts, your VATS Code is #1 and you are done!

If your Corvette does not start:

For 1986 to 1989 and 1997 to 2004 Corvette models:

• YOU MUST WAIT 4 MINUTES before trying resistor #2. You can wait more than 4 minutes, but no less than 4 minutes.
• After 4 minutes, remove resistor #1 from the plug and start again at Step 3. However, this time use resistor #2.
• Keep cycling through the numbered resistors until you find the one that allows your Corvette to start. Remember to wait at least 4 minutes between each cycle.

For 1990 to 1996 Corvette models:

If you have a 1990 to 1996 Corvette, follow the table below for wait times between each attempt. For the first three attempts, you must wait FOUR minutes. For every attempt after the third, you must wait TEN minutes. (Special thanks to Dave Perry for pointing this out!)

• After waiting the required number of minutes listed in the table below, remove resistor #1 from the plug and start again at Step 3. However, this time use resistor #2.
• Keep cycling through the numbered resistors until you find the one that allows your Corvette to start. Remember to wait the required number of minutes between each cycle.

Once you have found the VATS Code for your Corvette, you can use it to order the appropriate key blank. After ordering the key blank, you must bring it to a local locksmith to get the key cut to match your ignition lock.