PDM15 not waking up?

Hi all,

Have a strange issue going on

for context I am using an ecumaster battery isolator between the PDM and the battery with the engine kill wire from the isolator feeding the 12v ign in on the PDM (when the isolator is used to disconnect the main lead, it also switches the 12v ign to GND to turn off the PDM iirc), and using a syvecs S7+ ecu to send commands to the PDM via Canbus

the issue i am having is that when i power the car up with the isolator nothing from the PDM works - UNTIL I turn the key and turn the starter motor. doesnt matter how long for but this "seems" to cause the PDM to wake up.

For now im just hitting that starter to wake the car up before i do anything.

I had thought it might be ecu related or can bus related as at the time it was the fuel pump prime not working, but i now have some outputs set to "always on" (on if TRUE and TRUE) when the PDM is alive and they aren't powering up until i hit the starter.....

any help appreciated