98 Dakota w/2.5L
turns over, but will not start.
lights, horn, blinker, radio, etc. work
no spark
fuel pump does no power up unless I ground one prong of the relay with a jumper wire
no communication with PCM using a scan tool
have replaced the PCM, still no luck
all fuses, fusible links, and relays have been checked and checked again.
the odometer will sometimes flash the mileage when key is on and sometimes just display it.
Can you tell a novice how to find and check the ground and power wires to the PCM?
Or any other suggestions?

 

check the grounds. im thinking on that truck there are alot tied in on the passenger inner fender and on the drivers side framerail. just a thought

 

Suspect ASD relay may not be powering up. The ASD relay coil is energized by the ignition switch in run and start positions, which also could explain you lack of comm. w/ PCM and other problems. I'd be looking at that switch.