TL;DR: I have a 2000 dodge ram 1500 sport 4x4 and I got the "no bus" problem. Potential problems I know of, could include: crank potion sensor, obd-II port, loose battery ground wire, gauge cluster connections, cab light wiring, steering wheel connections, etc


So I just got a 2000 Dodge Ram 1500 sport. I got it because it was my friends cousins and he vouched for him and said it was a good truck. I checked it out I noticed that it didn’t have an obd-II port, it looked like it was kicked and got smashed. I was gonna walk away because I saw it did have a check engine like and I wasn’t gonna buy it not knowing what it was. However I remember from my dodge, which is a 94, that you can run the key three times and count the codes. So I tried it and “Voilà” there they are. It actually said the code too and it read P 0203 and P 0138 (this was cylinder 3 injector and oxygen sensors) I had injectors so I wasn’t worried but it turned out to just have the wiring just and the 02 sensors didn’t bother me. However I took it to me auto-tech teacher today (not in school technically anymore because of coronavirus but it’s a long story) and when I showed up to the shop he said he had to take a car to his daughter so I decided to take the time to fix the vacuum hoses for the climate control/blend door actuators well I got it to work but I noticed the green wire came out and I just put it back in while it was still running (I did all of the vacuum lines without the battery disconnected, not sure if that matter but I didn’t think it did) one I put the green wire it I say the abs light was on, the air bag, and the gauges weren’t working and it read “no bus” well I just unplugged the green hose thinking maybe some chance that was it and obviously it did nothing. However some other possibly options I think it could be. Like I said the obd-II port was broken so I decided to mess with it and I think once I started touched the connectors the no bus came back, as mine is intermittent and my vehicle still runs. It does it some times and others it doesn’t. Also my teacher pointed out it could be a loose connection in the instrument cluster or the steering wheel. The truck does have cab light which are wire to the light switch but I didn’t have them at at this time. Another possibility is there is a ground that is more or less just loosely under a bolt that is not a factory ground bolt. Not sure what the ground is for but could this be a possibility. And last one is my friend and his dad actually replaced the trans in this truck and said when they did it they pinched the crank position sensor and when they tried to start it, it wouldn’t start so they just pulled the trans slight out and pulled back the wires and it started. I apologize that this is so long but I would very much appreciate anyone’s help.

 

Ah the no bus... fun... secure your ground wire regardless of where it goes bad grounds do funny things I could tell story’s about a parts dakota I had but that’s another story. make sure you don’t have wires touching in the broken obd2 port. Pull the cluster out clean the contacts. Have they ever had it show up on them before? Has the dash been out for a heater core replacement?

 

Thank you for replying so fast. I asked the previous owner and he said he never had it happened nor did he have the dash out for the heater core. This truck does have 193K miles and 9 previous owners, so it is very possible that the dash has been out for a heater core; well, what is at least left of the dash. I tried messing with it, attempting to get it to do the "no bus" again but nothing I did would do it. so I disconnected the battery for about 2 hours and the code hasn't came back since.

 

The CCD bus is present on the OBD2 port although the actual required OBD2 functionality is using a different bus. I'd start with fixing the OBD2 connector, might be helpful in the long run anyways. There is a "joint connector" hiding somewhere under the dash that ties all the electronic modules together which would be the next thing to give the wiggle test.