No bu5 when Can bus is plugged in
 

I recently installed the digital overhead console in my 01 dodge ram 2500. I drove it home, and everything worked fine. I drove it to school the next morning everything worked fine, but that afternoon I turned the key on, the gauges did not move to their appropriate positions, the odometer flashed 4X read No bu5 and the overhead console read CCd. The truck still started but nothing else worked. I couldn't figure out the problem with the bus. But I noticed that the instant that I unplug the CAN bus plug, (the one that feed information to the console such as temperature compass economy etc) the gauges move to their proper positions, and No bu5 disappears, however the check engine light is on. The codes that I got when I did the key on-off trick were P1694, P1693, and P1687. I wiggled wire harnesses under the dash, Near the PCM and under the fuse box under the hood. I disconnected the batteries for 4 hours, and reconnected them. It didn't fix the problem but did take away code P1687 which is the cluster bus. I honestly knew it had to be a phantom code because the gauge cluster worked when the CAN bus was unplugged. It was a few days since the CAN bus was unplugged. I turned the key on, and noticed the check engine light went away. I drove it back home. Everything except the console since the bus plug was still unplugged was functional. shortly after I got back I plugged it in, and it did the same thing. My automotive teacher thinks that I need to take the truck to a dealer to get it flashed over. I agree but I'm also thinking could it be a bad Can bus wire and how do I check for it. Any advice would be appreciated.

Side note : I have been having a hard time finding out where to mount the outside temperature sensor for the overhead console. I have read that it is next to the hood latch striker but I can't find the place to mount it without the sensor getting crushed when I close the hood.

First thing your truck isn't CAN Bus it's CCD. Connecting the console won't cause it to lose communication, nite does it need to be flashed. If it worked you are good. Either you have an eclectical problem or your PCM is bad. The only time I could see getting it flashed is if the CTM didn't recognize it, which also means it wouldn't work

Agree with the above, the CCD bus is a very simple twisted pair differential signaling bus. If one of the controllers on the bus goes wonky or the wiring is open or short somewhere the controllers on the bus can't communicate which is what you are seeing. Sounds like the console is not original to the truck so assuming it's a used part it might well be bad.

The truck did not originally come with the console, and it is used, but in the time that I did work which was for the 1st day, everything was working. Both my automotive teacher and the people at the dealership (chrysler, dodge, jeep, ram) think it needs to get flashed over based on what I told them. They told me that the computers get "confused" with a new computer installed that didn't used to be there. The console and wire harness came together and was in another truck that also did not originally have the digital console. I don't think the PCM can be bad because with it (the CAN bus for Ccd) unplugged the gauge cluster and everything worked fine, and hasn't had any issues when driving, even at operable temperatures.

You don't have CAN BUS on a CAN BUS vehicle yes it may have to be flashed on a CCD BUS you do not have to.

I contacted the dealer ship (Chrysler, Dodge, Jeep, Ram) later today. I told them the same things listed in this forum. They were not able to flash it over because they don't support older vehicles like mine, but then told me that it doesn't need to get flashed as you said MoparFantatic21. They are thinking that it is the wiring, or the PCM may be at fault. I don't think it is the wire harness from the fuse box under the dash, up the pillar, then to the console. The console readings are bright and clear when the truck is on. My next target would likely be the wiring that runs from the PCM to the fuse box (under the hood) and then eventually runs through the firewall and then the box with the plug for the Ccd bus.

Everything I just said. If it only happens with the overhead console plugged in it's the PCM

Thank you for the advice, I will tap into it. I will let you know if it fixes the problem.

I have not fixed the problem yet, but another thing I have noticed is that my overhead trip computer will not dim when I turn my lights on. It did when it worked. My odometer on the gauge cluster and the radio will still dim. I switched consoles and no effect on the dimming.

you have to have a bad wire somewhere