2004 Cadilac CTS 3.6 No crank no start

[koziolek]

car came to shop with no start condition,
when starter relay bypassed the car started and run no problem
turn off the car try to start again no issues ,when park for longer than 15 min
does not start again until starter relay by passed.
when car runs can communicate with ecm normally when turn off and wait until
no start condition appeared back no communication with ecm .
check the power and ground all fine
Tried to program new PCM but no chance to adapt it because no communication with it.
All other module respond to scanner with no problem
One DTC U1000 Class 2 data link malfunction.

[koira]

Hah, funny thing is that I have this Opel 2.8T in my shop with similar situation.
After about 15min no communication with PCM.
PCM tested on bench and work fine but not installed in car. Some supply must be missing but have not found it.
PCM is Bosch ME9.6, I believe yours is the same.

[koira]

One correction to the issue, does the same thing on bench. So I must come to conclusion that the PCM is faulty.
It is alive when powered but does not respond to can bus without starting car first by activating starter manually.

If you get yours to work please inform what was resolution.!
Also if someone has knowledge on fault repair in PCM please give hints.