I have an 06 Fiat Ducato 100 multijet van which fails to start.The ignition lights is minus the preheat symbol and after a few seconds the locked symbol comes up(solid).The engine turns over very well but will not fire.I have checked the fuse box underbonnet and all connections seem ok.I have changed the fuel filter in case that was the reason.I have had the key checked for communication with the ecu.After exhaustive checks I have found that there is no power to fuses F11,17 and 22.If I put an independent supply to any 1 of these 3 fuses the fuel pump works and when the key is turned all lights come up,preheat as well,and the engine will start and run perfectly albeit with the engine management light on.When the power to the fuse is removed the engine stops.I am assuming rightly or wrongly that these fuses are controlled by the immobilizer so I suspect an immobilizer fault.Can anyone tell me where, on this model,the immobilizer is situated and whether the fuel pump connection can be bypassed.
If I am barking up the wrong tree I would appreciate being pointed in the right direction.

If the immobilizer could be fooled with a jumper wire, the device would be worthless.
What it does is far more complicated. It sends a code to the ecu firmware that suppresses the command pulses to the fuel injectors.
In your case there is DC missing on a group of fuses, so there probably is a relay contact not closing. Worst case is a damaged ecu output, more likely is a corroded contact or a bad relay.

It appears that you have lost the supply to those three fuses. Maxi fuse F70 on the fuse box feeds battery volts to F11/17/22 via relay T09 {engine fusebox}.

I have attached a drawing but have not had time to study it to find what activates T09 but it would be worth checking F18.

I have checked fuse f18 and all the fuses in the engine fuse box ar ok.I am unably to identify relay TO9 is it in the same box?

I cannot find a fuse F70

cory spaans said:

I cannot find a fuse F70

Click to expand...

F70 is one of the Mega fuses on the block that is connected directly to the battery positive terminal. I presume this is ok because it provides power for several circuits.

T09 is a relay inside the engine fuse box.