Weird problem no bus

[CL2000]

Truck info 2000 auto, p pump. P1694 no buss code
So this happend 2 years ago and it randomly fixed it self. It has been fine and has started acting up again. So it acts like a bad ECM but is not. I have a wait to start light that flashes, no gauges, not charging and no lift pump. So in the morning it is fine..,, drive it some where park, come back an hour later and it has the isue sometimes I can shut it off and start it back up and it is fine. I have swaped ECM, and PCM with known good ones with no change. I have checked the bus wires at ECM and PCM and they check fine. I have unplugged every module in the truck and no change. I have checked all fusses and moved relays around. I have changed the ctm. I do not have map sensor, iat sensor, or cam sensor. I'm trying to get a friend with a drb 3 to come by so I can do the test on it. The only thing I can think is maybe a bad crank sensor, engine harness has a bad wire or there is a problem at the big plug under the dash. Also it has new battiries, and I have cleaned and checked all grounds including the ground in the engine harness.

 

[jlbayes]

my truck is doing something similar and i am thinking cam sensor is causing the issue. i know the 2000 has cam and crank sensors, check both.

 

[CL2000]

I don't run one. I only have a crank sensor. I'm going to try and unplug it tonight

 

[CL2000]

So this is my exact problem Very strange PCM/ECM issue - Page 2 - Competition Diesel.Com - Bringing The BEST Together I have put a new water temp sensor in and oil presure sensor in. I have disconnected the apps and all Other sensors that are on the same ground and 5v refrance circuit with no changes. Anyone have any ideas?

 

[sstockton]

You might have checked them already, but what about those big cam lock connectors under where the fire wall protrudes out over the engine compartment. On the drivers side just above the valve cover. I had that happen years ago where the lock was knocked out of position but the plugs were still connected. It was hard to even tell that anything was wrong there, and I'm pretty surethat was the code that was displayed.
Sean

 

[CL2000]

I have checked them more times than I can count. It is completely diffferant when I disconnect those connectors.

 

[ericjk42002]

I have checked them more times than I can count. It is completely diffferant when I disconnect those connectors.

Sounds like a crank sensor.

 

[CL2000]

Nope no change when I unplug it and I have even plugged another one in.