OK I'll start with my truck is a 99 24v auto. All stock aside from a beans sump and a fass 150. I had a edge ez but it's been removed. Also I just replaced the vp44 with a used vp44. Before I replaced it I had a hard set p1689 no communication between ecm and vp44. Once I put the replacement VP in the code immediately went away and right before I had all the injectors bled(almost had it running) it threw the p1694 in both ECM and PCM and then kicked me out of the bus connection. Still have power at the data link connector. 

Now I'm unable to connect my scanner(Autel Maxidas) to either, no tach signal while cranking, no wait to start light, no lift pump signal, and pin 7 on the vp44 isn't getting power. Likely because the fuel pump relay isnt getting the correct signal. If we put power to the wire from the FP relay that goes to pin 7 on the vp44 we can hear the VP click on. I've tested all fuses and grounds with my power probe 3 and all test good. I pulled the ECM plug and tested all the pins and it's getting correct power and ground from pins 48,49,50. I did notice all pins related to Cummins bus showed no signal or anything on the power probe. Pins 40 and 41 show 0.0 with key off and a little over 2v with key on. I may be making this harder than it should be but I'd like to rule out any other possibilities before replacing the ECM... Any help is greatly appreciated.

Well its in my '99 service manuals. but the info isnt the greatest like most the service manual stuff\

 

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Wow way to thread jack over a seat belt light lol.

Found the draw was from me putting the key on power wire to my external voltage regulator was on the wrong fuse after i put the fuse block back in. 

Good to hear you found the issue. 

 

I think we like to call it thread enhancement rather than jacking. A lot of natural curiosity around here. No offense meant nor taken. Now to