Originally Posted by Superfragl

Hi all,
I recently acquired a 04 Crossfire limited in non running condition. I hope I can get some advice from the forum.
When I turn the ignition on dash lights power on, radio, doors, etc, however - the fuel pump will not prime and the starter will not crank. PCM will not communicate via OBD2. Cooling fan will run at full speed (which might be a separate issue).
Previous owner bought a replacement PCM, but did not reprogram it. I plugged the replacement PCM and surprisingly the fuel pump primed and I had the car crank and start for 1 sec. - twice, then no start again - which is the way it is supposed to be, SKREEM is not recognizing the code from PCM.
Then I reprogrammed the replacement PCM with original vehicle data (VIN, security pin), installed it, connected the battery. The car started and ran for 15 -20 seconds just fine, then died. Same situation again - no fuel pump, no crank, PCM not communicating. I would disconnect the battery, touch the leads together for 10 sec, connect it back - still nothing. I left the battery disconnected for 2 days, came back and connected it, car started fine and died 15 seconds later. So if I leave the battery disconnected for a longer time I will be able to get everything working for 15 sec, even if I don't start the car and just turn the ignition on, PCM will communicate for 15 -20 seconds and then nothing..
I have checked the RCM and resoldered ALL spots, took relays apart and checked the contacts, made sure the circuits are closed at the socket pins while 12V is applied to the relay coils.
What could it be?? Is there a security feature that is preventing it from running? What else can be checked?
Thank you.