t5 start then cut out imob issue?

Ive put a new chassis on my 1989 90 and ive done away with the 200tdi and gone for a disco td5 lump and box. Over the last year ive been buys the bits i need to get this thing to work (External fuel pump ect ect)

Last friday i managed to get it to start but only by bypassing the black and orange wire from the starter relay straight to earth, on the wiring diagrams it just showed it as going to the alarm ecu (green box i believe is AMR6429) which i dont have. My understanding was that the immobiliser on a td5 only stopped the starter kicking in and these things could be bump started.

So without ranting on basically i took the black and orange wire straight to earth from the starter relay, this allowed it to start up but it died after about 3 seconds. Ive googled this problem and from what i can gather there is a signal on the green and grey wire from the green immobiliser box AMR6429 to the ECU which keeps the engine going..

My question is 1: is what I'm saying correct
2: do i need to buy AMR6429 and plug it in behind the clocks, with a key fob to go with it and if so could i get one with a fob from a disco 1.
3: could i bypass this green box all together and keep it running?


Thanks and sorry for the long post

couldn't tellyou about a defender td5 but a disco td5 PCM needs a signal from the body module or it wont run. I guess a defender is similar...needing a signal from somewhere.

There are ways and means round about it but nothing free

picked up the green immob box and a key fob from a friend who broke a disco 300tdi as they have the same part number, this now lets it crank if i use the fob or doesnt let it crank if it is immobilised. Just need to get some fuel for the tank and i can try it and see if that makes it sit at idle.