'Secret Switch' immobiliser

[maz]

best way is to immobilise the engine by putting a secret switch on the fuel cut off solenoid, it will never start and they would have to tow it away!

Currently looking into additional security and found this buried in another thread about wheel clamps. Like the sound of it but have no idea how to fit it. Is it only a DIY thing or could I get one fitted by someone who actually knows what they're doing?

 

[Silver-Fox]

The simplest cut off is to find the negative feed wire to the starter from the ignition and put a switch on that.

Hide the switch away where it’s not obvious.
The vehicle will never start.

 

[Two on Tour]

i was thinking of fitting a cut off switch to the underfloor fuel pump on my 2017 ducato but i am concerned that it will throw up a fault code, if anybody has done it which colour wire do i need the put the switch in that i will hide in the cab somewhere

The terminal arrowed #4 in the image is the positive for the lift pump, which is the nearest to the driver's seat in a right-hand drive van.
Does not throw up a fault code on my van.

 

[Bandos]

Simple relay circuit

 

[Two on Tour]

Simple relay circuit



View attachment 991406

Why use a relay when a simple switch will do the job ?

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[Bandos]

It is good practice to install a relay as it takes the load off the switch.

 

[Two on Tour]

It is good practice to install a relay as it takes the load off the switch.

The fuel tank lift pump draws about 4 amps, which is only running for a short period when the engine starts, as it's only priming the diesel pump during the engine starting phase.

 

[daleman]

Does that mean that the engine could possibly start without the lift pump running? For example if the engine has only recently been turned off, or does the fuel drain back to the tank?

 

[Two on Tour]

Does that mean that the engine could possibly start without the lift pump running? For example if the engine has only recently been turned off, or does the fuel drain back to the tank?

Basically, yes, my engine will start with the switch in the off position if the engine has been run and still warm/hot.

 

[Bandos]

The switch/relay should go across the Diesel fuel pump not the lift pump. As Two on Tour says would serve no purpose on the lift pump.