Hobbies Cars & Motorcycles How to Disarm a Vehicle Theft Security System Share PINTEREST Email Print ByeByeTokyo/E+/Getty Images Cars & Motorcycles Cars How Tos Buying & Selling Basics Reviews Tools & Products Classic Cars Exotic Cars Corvettes Mustangs Tires & Wheels Motorcycles Used Cars SUVs Trucks ATVs & Off Road Public Transportation By Matthew Wright Matthew Wright has been a freelance writer and editor for over 10 years and an automotive repair professional for three decades specializing in European vintage vehicles. our editorial process Matthew Wright Updated February 25, 2019 If you leave the front doors unlocked, the alarm shouldn't arm itself. If it is arming itself when the doors are not locked, there is likely a problem that needs to be repaired. You can disarm the VTSS by unlocking the vehicle with the key in either front door lock cylinder or using the Remote Keyless Entry (RKE) transmitters. This will not permanently disarm the system, but must be done each time after locking the vehicle. If you want to permanently disarm the system, you will need to see a service center and discuss it with them. User Error or System Problem First, determine whether you simply don't understand how the system is supposed to work. Below are the instructions for how it should work. If you are doing everything as you should and the alarm is arming itself when it shouldn't, it needs to be repaired. This is how the Vehicle Theft Security System (VTSS) operates. The Vehicle Theft Security System (VTSS) monitors the vehicle doors, liftgate, and ignition system. If an unauthorized use or tampering is detected, the system responds by sounding the horn, flashing the exterior lamps, and providing an engine no-run feature. If you have a vehicle immobilizer system, it can only be disarmed using the Remote Keyless Entry transmitters. Enabling the Vehicle Theft Security System The VTSS engine no-run feature is disabled when it is shipped from the factory. This is done by programming within the Powertrain Control Module (PCM). Before a sale, the VTSS no-run feature is enabled by electronically advancing the PCM engine start counter using a DRB scan tool. Once the VTSS engine no-run feature has been enabled, it cannot be disabled unless the PCM is replaced with a new unit. The same is true for the Vehicle Immobilizer System. Arming the Vehicle Theft Security System Passive arming of the VTSS occurs when the vehicle is exited with the key removed from the ignition switch, the headlamps are turned off, and the doors are locked using the power lock switch. If any of these things are not true, it won't arm passively. It also won't arm if you use the key to lock the front door or the liftgate. Active arming of the VTSS occurs when the Remote Keyless Entry (RKE) transmitter is used to lock the vehicle, even if the doors and/or the liftgate are open when the RKE transmitter Lock button is depressed. However, the VTSS arming will not be complete until all the doors and the liftgate are closed. The VTSS will also arm itself if it senses the battery has been disconnected and reconnected. You will have to disarm it after power-up. Disarming the Vehicle Theft Security System Passive disarming of the VTSS occurs when the vehicle is unlocked using the key to unlock either front door or the liftgate. Active disarming of the VTSS occurs when the vehicle is unlocked by depressing the Unlock button of the Remote Keyless Entry (RKE) transmitter. Once the alarm has been activated (horn sounding, lights flashing, and the engine no-run feature), either disarming method will also deactivate the alarm. Depressing the Panic button on the RKE transmitter will also disarm the VTSS, but the horn will sound and the lights will flash for about three minutes as part of the Panic feature. Refer to Power Lock Systems for more information on the Panic feature. Tamper Alert The VTSS tamper alert will sound the horn three times upon disarming if the alarm was activated and has since timed-out (about eighteen minutes). This feature alerts the driver that the VTSS was activated while the vehicle was unattended. Circuit Operation Each door, the liftgate, hood, and the liftglass in the liftgate have an ajar switch that connects to the Body Control Module (BCM). The ajar switches are normally open when the doors, liftgate, liftglass, and hood are closed. When one of them is open, its ajar switch closes and connects the BCM to ground. In response, if the Vehicle Theft Security System is armed, the BCM starts the alarm.