VATS (Vehicle Anti-Theft System), otherwise known as Passlock, was introduced by GM on the 1986 Corvette because the Corvette had become the number one target of car thieves. Corvette thefts dropped so impressively after VATS was implemented that GM expanded the system in 1988 to the Camaro, Firebird, and Cadillac Seville. Before long, VATS was standard equipment on all Cadillac vehicles and on many other Chevrolet, Pontiac, Buick, and Oldsmobile vehicles.
The system itself operates on a very simple principal. In addition to the standard side-bar ignition, there is a resistor embedded into the key. When the key is inserted into the lock and turned, an electrical current runs through the resistor. The amount of current drop caused by the resistor is measured by a computer. If the current drop matches the pre-set value stored in memory, the car is allowed to start. If the current drop is higher or lower than the pre-set value, the vehicle will be prevented from starting even with the correct key for several minutes. No alarm sounds and the only indication that the vehicle has been disabled is an indicator on the dash. The time delay feature was the main reason that VATS proved so successful. Studies showed that if a would-be car thief could be slowed down, even for a few minutes, they would look for an easier target. VATS equipped vehicles soon became some of the least stolen vehicles on the road.
The downside is the system can eventually erode and cause a no-start, intermittent start, or start then die issue. There are two ways to determine if the VATS system is the cause of a no-start condition. The quickest way is to look at the security indicator lamp on the instrument panel. If it’s flashing after an attempted start, the fuel disable command has been energized. The second method is to use a scan tool to check the antitheft or fuel system status parameter. If the parameter shows “fuel system disabled” or a similar description, then it’s a VATS issue.
We have the ability to disable the VATS feature within the PCM which will eliminate the no-start, intermittent start, or start then die issues. We offer a single-item passlock disable tune that will disable the security feature in the PCM. We just need the PCM from the vehicle mailed to us to be updated.
If you'd like to speak with us more about this solution or proceed with a tune, please visit our Tuning Services page or our Contact Us page. Additionally, our frequently asked questions page has answers to many common GM and tuning related questions.