Ph2 Immobiliser questions

[Beaniemoo]

Right, need answers here from people who KNOW their stuff.
I have a 51 plate, Ph2 Clio 172 with an immobiliser problem.
Turn the ignition on and the red immobiliser light stays on in the instrument cluster, if you go straight to cranking it'll crank a couple of times then stop, or if you turn the ignition on, wait, then go to crank it won't crank at all.
All standard immobilising I think.
I have checked the immobilising relay in the engine bay and it is not switching (yet again standard immibilising I think)
I have checked all the feeds and wiring to the immobiliser relay and it is all working fine, if you disconnect the ecu and earth the pin you get fuel pressure etc, so thats all ok.
As I have a running ph2 172 laying around, I have also tried a know good, ECU, UCH, Key reader and key, but still the same fault.
I know I have plenty more to check but was just wondering if anyone knew any indepth information on the immobiliser to speed up or aid diagnosis.
Are the ECU, UCH, key and reader the only things that are involved in the immobiliser?
Is the instrument cluster or anything else involved in any way?
Also to speed up the wiring checking, does anyone have the wiring diagrams or pin designations for the immobiliser? Key reader-UCH, UCH-ECU?
How do the control units communicate? Is it done via CAN? If so are there any other control units on the CAN network?

Any help at all would be gratefully recieved
Thanks in advance

Moo

 

[Sean6545]

Normally means the injection computer isnt recieving or recognising the immo code. (or the ECU isnt being powered).


Try, turning the ignition on for 30 seconds then off, lock and unlock the car and try it then.

 

[Beaniemoo]

I did read that somehwhere and have tried it, but that didn't do anything.
Does anyone have the wiring diagram or pin designations for ECU or UCH so I can check all the feeds and earths?

 

[Beaniemoo]

Bump?