2. GPS Tracking Systems (with Immobilisation)
- Anti-Theft Devices
GPS units with immobilisation sound like a strong anti-theft solution, but in real-world thefts they still end up being surprisingly ineffective.
Here are the reasons — explained safely and without providing any techniques thieves use.
1. Thieves have a new way to locate battery powered GPS units.
A magnetometer is simply a sensor that detects magnetic fields.
Some handheld devices and scanning tools include magnetometers that can identify:
- Electrical components producing magnetic fields
- Metallic objects with magnetic signatures
- Electronic circuitry operating inside a vehicle
GPS trackers — especially cheaper or older ones — often contain:
- Small motors (for vibration alerts)
- Switching power supplies
- Magnetic mounting plates
- Metallic housings
- Coils or inductors inside the electronics
These can create detectable anomalies in a magnetic field, which certain scanning tools may be able to identify when someone sweeps over an area.
Why this matters for security professionals
Security installers and law-enforcement use these tools to:
- Locate hidden electronics
- Sweep vehicles for unauthorised tracking devices
- Detect tampering or unknown hardware
The point is not that thieves “use” magnetometers, but rather that magnetic signatures make some trackers more visible to anyone using detection equipment.
2. Immobilisers built into GPS units are usually very basic
GPS-based immobilisers normally interrupt:
- The starter motor
- The fuel pump relay
- Or an accessory circuit
These are old-style immobilisation points that modern thieves rarely rely on anymore.
If a thief uses an electronic method to start the car (CANBUS manipulation, key cloning, relay theft, etc.), the GPS-based immobiliser often never activates, because it expects a traditional “turn of the key” event.
3. The immobilisation circuit is easy to defeat
The immobiliser is part of the same wiring as the GPS unit.
So when the thief finds the tracker:
- The immobiliser wiring is right next to it
- Removing or disconnecting the GPS also removes the immobiliser
- Cutting power disables both instantly
In other words, the GPS and immobiliser are a package — disable one and you disable both.
4. If the GPS loses signal or power, the immobiliser can’t be triggered
Immobilisation usually relies on:
- The GPS having power
- The GPS having mobile network connectivity
- Remote commands being received
Thieves typically cause the vehicle to lose power or lose signal anyway (without needing any sophisticated methods).
Once this happens:
- The tracking stops
- The immobiliser can’t be activated
- The system becomes “blind”
A device that relies on communication can be defeated simply by preventing communication.
4. GPS immobilisers react after a theft begins — not before
Most systems only allow immobilisation:
- Once the vehicle is stopped
- Once the thief parks it
- Or once the owner notices it’s missing
This means the car is still driven away initially.
Many stolen vehicles are:
- Hidden in underground carparks
- Taken to rural properties
- Put in shipping containers
By the time the owner tries to immobilise it, it’s already unreachable or stripped.
5. Organised thieves expect immobiliser-equipped trackers
Professional thieves assume every valuable vehicle may have:
- A tracker
- A basic immobiliser
- A SIM-card-based alert system
Because it’s expected, their first focus is always to locate and disable electronics inside the car.
The fact that GPS units include immobilisation doesn’t surprise them — it just means they remove one device instead of two.
6. Immobilisation doesn’t stop most modern theft methods
Most modern vehicle thefts don’t involve starting the engine in a conventional manner.
These methods allow thieves to drive away even if a starter/fuel circuit is blocked.
You don’t need to explain how — it’s enough to know GPS-based immobilisation targets old-style theft behaviours, not current ones.
In simple terms
A GPS with immobilisation is ineffective because:
- The unit is easy to find
- Removing it disables the immobiliser
- The immobiliser only blocks old theft methods
- It relies on power and signal
- It reacts after the theft begins
- It doesn’t integrate with the car’s CANBUS
- Thieves expect and neutralise them as part of their routine
It’s better than having nothing — but it’s not effective against modern, targeted theft.