Ok guys, i've finished wiring up my d16z5 swap in my previously twincarb shuttle. I've done this by putting a small part of a crx wire loom into a shuttle (from engine harness to ecu, that sensor under the dash and the main fuel relay and I've wired up all remaining wires accordingly).

What is working now:
Main relay
Starter
fuelpump

However, the ecu does not work

I've checked the following:
power: the ecu is getting power from the battery at all times ( at vbu)
Power from key in position 2: The ecu gets power from IGP1 and 2 when the key is in position 2
start contact: the ecu gets signal from the STS wire when you start the car
Ground: PG1 and 2 are grounded from an existing wire that runs behind the dashboard. The main relay is also grounded from this wire and it does not have any problems. I've tried grounding PG1 and 2 separately at a different point but that does not have a different effect.
I have also checked the ecu in another car and it works fine

The only thing I see is that when I put the key in position 1 I see a small bleep from the ecu led for a short moment and then nothing. When I put the key in position 2 the same happens. However there is no check engine light on on the dashboard.

What can I do and what can I check?