97 Sebring PCM

I have been working on a 97 Sebring Convertable at work and i can't figure out what is going on. Its had two different computers put into it and a fuel pump. Now the third computer in the car is fried and i cant figure out why it keeps buring the PCM. When i hook up a scan tool its says there is no responce from the PCM. Ive checked the autoshutdown relay, the PCM ground and the power to the computer and i have a good ignition output signal to the PCM. Im out of ideas and any help would be APPRECIATED.