Hello,
Problem - No Bus, but run great. 47K miles.
I tested 5V where I read to be tested - all good from what I can tell. New Crankshaft position sensor installed by a so-called "mechanic" to fix the no start after the engine was warm and shut off - had to wait as much as an hour before the engine would start again. I replaced the Distributor Pick up coil which fixed the no start problem after it was warm and turned off the engine. Still getting a No Bus reading. Well, if anyone could help, that would be great. There are other problems, but one thing at a time

 

The "No Bus" message indicated a loss of communication between the PCM and the digital portion of the instrument cluster. It could be from a faulty wire, connector, or the cluster has gone bad.

 

After testing all of the sensors (3) attached to the carb today, and after nearly 3 days trying to find a short somewhere following all the information that I found online, I just reconnected the connections and the "No Bus" did not show up. Crazy - it looks just like it might have needed to remove all 3 connectors and reconnect to establish a better connection - crazy! Next - ABS and brake light...

 

I think it was only the need of reconnecting the sensors on the carb to establish a better connection. So far all good. We'll see. Very odd! Thank you! Now I need to figure out the ABS and brake light. Any common problem fixes for the ABS?

 

One other thing I did, which I don't know if it matters or not, but I stuck my picky into the carb because it was whistling and pressed on the Idler valve sensor and moved it in and out to free it up to stop the whistling. That connection read 0 volts on all for pins when I checked it. Don't know if this had anything at all to do with the fix? I'm an ex-airplane mechanic, not a auto mechanic. Lol

 

I hope a "picky" is a finger!
Yes we call that the finger trick. By covering the air inlet port to the IAC valve it forces the valve to operate and often solves poor idle air sucking sound issues.

 

Funny "pinky." lol Oh shoot! 'No Bus' came back. I love working on my BMW. Hate working in these Dodges - half *** engineering and cheap parts. Fix one thing and another part goes. More sensitive than a _____. (fill in the blank)

 

ABS, Cockpit Cluster and PCM are connected to the bus. The bus is differential (about 2,5V each line) and has to be terminated by 120Ohm resistor (this is done inside the units). Powering the bus is also done from within the units. The problem with bus systems is that one broken communication unit could kill all communication.
Check the 5V supply of your PCM as it's source is used to power sensors and bus communication. Maybe after a while and when the pcm gets heated up the 5v source will run into issues.