3. Secondary Immobilisers (Kill Switch, Fuel Cut, Relay Controlled)
- Anti-Theft Devices
Moderately Effective
Kill switches sound like a solid anti-theft measure, but in real-world modern vehicle theft, they’re often far less effective than people expect. Here’s why:
1. Thieves know exactly where they’re usually hidden
Most DIY or workshop-installed kill switches end up in predictable places:
- Under the dash
- Near the fuse box
- Behind the kick panel
- Inline with the fuel pump circuit
Professional thieves—especially the ones targeting Holdens, Toyota, Nissan, and other high-value models—check these locations first. Many modern thieves can locate and bypass a kill switch in minutes.
2. They’re easy to bypass with basic tools
Because a kill switch physically interrupts a single wire (starter, fuel pump, ignition, etc.), thieves can often:
- Bridge the cut wires
- Run a new power feed
- Jump the starter
- Replace the relay or fuse you’ve interrupted
If a thief can access the wiring, the kill switch becomes just an extra step — not a barrier.
3. They don’t protect against modern electronic theft
Kill switches were designed for old-school hot-wiring.
But today’s theft methods don’t rely on that anymore:
- OBD key programming
- ECU swapping
- Relay attacks on keyless systems
- CAN bus injection attacks
A kill switch does nothing to prevent thieves from tricking the car into thinking it has a valid key.
4. They can be completely bypassed by towing
If someone wants the car badly enough, they can simply:
- Tow it onto a tilt-tray
- Drag it a few metres and lift it
- Use a wheel-lift tow dolly
A kill switch only stops the vehicle from starting—not from being physically removed.
5. They can cause electrical issues if installed poorly
DIY kill switches can often lead to:
- Random electrical faults (esspecially on newer model vehicles with advanced computer systems)
- Starting problems
- Blown fuses
- CAN network disturbances
To put it simply, modern vehicles don’t like having their wiring modified.
Additional Cons
- Physical switch can easily be found: For daily use, a kill switch would need to be in a position of easy access for the user, meaning that this may narrow down the time in which it would take the thief to find the switch.
- Wiring can be traced back to the switch if the thief has enough time.
- Not effective against OBD key reprogramming unless integrated well: This means thieves can erase and program new keys. When you get back to your vehicle (if it’s still there) you will not be able to use your key to start the vehicle.
- Unreliable as you are relying on yourself to arm/disarm. Car is left vulnerable if you happen to forget to turn the kill switch on.
Whilst labelled as “Moderately effective”, we say this with caution.