I posted a while back about a no bus code on my 2001 ram 1500. Thanks for the replies. Although I still havent found the problem, but I have another issue or might be linked? The fuel guage has read empty since I got the truck, I put 20 gallons in it so I know it is pretty much full. I disconnected the cpm ports and replugged them. Started the truck and the guage jumped to full for maybe 30 seconds, than I hear a ding and it falls back to empty. I disconnected the battery and waited 30 minutes or so, hooked up the battery and started the truck. The same thing. It jumps to full and than the ding and falls back to empty. Any suggestions?

 

When you first start the truck, all the gauges will test. Sounds like that is what you are seeing. I think the Fuel gauge goes thru the PCM as well, so, need to solve the No Bus problem, and it may start working.