GM Service Theft Deterrent System: How to Fix

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Most GM vehicles built in the last 20+ years have a theft deterrent system.  The system disables the vehicle’s fuel pump, ignitions system, or starter if unauthorized access to the car is detected.  

When your vehicle has the service theft deterrent system message, the system will not let the vehicle start.

The two most common causes of “Service Theft Deterrent System” are a bad battery or a new/faulty key.

Resetting the system takes about a half hour and is something you can do yourself at home.

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Service Theft Deterrent System Causes

Here are the most common reasons the service theft deterrent system warning can occur.

Dead Battery

If your GM vehicle has a low or dead battery for an extended period, it can mess with the theft deterrent system.

A weak battery or discharged battery won’t make it through the half-hour-long process of resetting your service theft deterrent system.

Newly Cut Key

If you have a new key cut, it can trigger the service theft deterrent system message.  You’ll need to turn the key and wait for the theft deterrent system to learn it.  Jump down to the next section for exactly how to do that.

Other Causes

Other causes of the service theft deterrent system message include a bad key fob, a blown security system fuse, or ECM issues.

How to Fix “Service Theft Deterrent System”

There is a way to get rid of the service theft deterrent system message on most modern GM vehicles.  Here’s what to do:

  • With a fully charged battery, put the key in the ignition and turn it like you are going to start the engine.  Leave the key in the on position. You’ll see the little padlock symbol, security light, or service theft deterrent system message.
  • Once the padlock goes out (takes about ten minutes), try and start the vehicle again.
  • If you repeat this process three times, the key should start working, and the padlock symbol should disappear.

What is GM’s Theft Deterrent System?

GM’s theft deterrent system goes by the name “PASSlock,” or just the theft deterrent system. However, no matter what name it goes by, it still functions in the same basic way.

A theft deterrent system is designed to make your vehicle harder to steal.  It is an alarm system, and it’s an immobilizer (makes it where the truck or car won’t start)

Given enough time, almost any security system can be bypassed.  A security system aims to alert you and make the hassle of stealing your vehicle and possessions too great for the potential thief.

Parts of the Theft Deterrent System

  • Immobilizer– An immobilizer is an anti-theft device installed in a vehicle. It uses electronic chips embedded in the key to send a signal that the car’s computer must recognize before it will start. This prevents unauthorized people from being able to start the vehicle and steal it.
  • Vehicle Sensors– Newer, modern security sensors on a vehicle include motion sensors, which are triggered when the car is moved; tilt sensors, which detect any change in the angle of the vehicle; and proximity sensors, which detect when someone is too close to the car. Additionally, infrared sensors can detect when a key fob is within range of the vehicle and will only unlock the doors if the right signal is sent. Hood latch, door lock, and key recognition sensors have existed for decades.
  • Key Fob– Key fobs are an essential part of vehicle security, as they use advanced electronic chips embedded in the key to send a signal that must be recognized by the car’s computer before it will start. This ensures that only authorized users can unlock and start the vehicle, protecting it from theft.

What Does Service Theft Deterrent System Mean?

The Service Theft Deterrent System is an alert message that vehicle owners may receive when their anti-theft system is not functioning properly.  The two most common causes for it are a dead battery and key issues.