How can I activate the Immobilizer on my Peugeot Boxer 2001?

Previous owner had a engine crash and replaced it with a used engine, but he could not get the car to start.
I think it is the immobilizer because the manual says a code-light in the instrument panel should either light up if working OR light up and flash if its something wrong, but it does not light up at all in my panel.
I have checked the lightbulb behind the instrumentpanel and the wires and its ok.
Someone said it could be a large fuse for the immobilizer that is blown but where is that fuse located?
I have checked all the fuses I can find.
Any help is MUCH appreciated !