Fix PassKey III system Car won’t start security light on If you own a GM vehicle with PassKey iii system or a previous PassKey II or PassLock system and have a car won’t start security light on, this article is for you.   GM’s history of antitheft systems VATS and PassKey I GM’s first attempt at vehicle antitheft was called the Vehicle Antitheft System (VATS). It’s really the first PassKey system. Each key has a resistor pellet embedded in the key. When you insert the key, electrical contacts mounted on … Continue reading PassKey III system