Just bout a 2000 model 2500 from insurance salvage that was wrecked in the front passenger side not running with 364k. Started working on it and would not start. Plugged my code reader and no codes so I put my pressure gauge and would not hold pressure spinning over and wouldn't get past 10 psi if you cycled key 3 or 4 time with out cranking. So I install a raptor 100 and have plenty of pressure and still can not get it started/bled out. Pumped seemed to cut on with key switch and off when key is off. Then all the sudden I could not get pump to cut off unless I physically unplugged it. So just to reconfirm there were no codes I plug my reader back in and viola, my pump turns off and cut key on and there is a p1689 (communication error between up and ecm)? And now lift pump relay just seems crazy and have to plug obd2 connection up to make it stop after you turn key off. Is this indecative of bad ecm or pcm? I called previous owner as his name and number was on the side of the truck and he said it ran great before it was wrecked but asked him if he tried to start it afterwards and said it cranked up and shut off shortly after and wouldn't start back. I read somewhere while googleing this code that to rule out ip you can unplug connector to pump and bottom right pin jump 12 volts and top right ground out and it should idle is this correct?