Can somebody give me a rudimentary rundown on what it is and where it is connected? I picked a 2000 Durango that likely has problems within the underhood wiring harness and a NO BUS in the display. I've got some manuals on order. I've got a fairly good working knowledge of the inputs and outputs of the computer, but the bus is something I haven't had to deal with before.

The reason for putting this here as opposed to the truck section is that the CCD bus is also used in passenger cars and I am looking for as many answers as I can get. Thanks.

pull the cluster and disconnect the connectors, spray em out with contact cleaner and reconnect. that fixes alot of no bus problems.

yep, usually bad connections, unless someone was hacking and slashing in there.
Chrysler Collision Detection (CCD) Bus is how the computers (PCM,CAB {ABS}, BCM, IPC) 'talk' to each other. High speed 'blips' of voltage over a party line, with each computer picking up the signals meant for it.
You will probably get confused the first few times through the manual. The BCM one is usually the one with Communication codes.
Buried in the first few pages is the sentence (paraphrasing here) "Codes with an * (asterisk) in front of them are customer complaints."
Like a customer is going to complain that the IPC is not getting a Bus signal!
Anyway, try to pull codes and get a realistic trouble shooting chart to start with.
BTW, if the (for example) Instrument Panel Cluster (IPC) is not communicating with the other modules, the OTHER modules wil report the lack of communication, NOT the IPC (It's not talking, remember?)

Ok, so it's a network that connects each computer in the vehicle, right? I can't really get the codes yet since I only had enough charge on the battery to get a few cranks. I have the manuals on order, but I plan to check all connections under the hood (it seems to have sprayed coolant or rusty water everywhere at some point) and I plan to fix the replacement battery terminal clamps (the ones that have a clamp for the wires....). I've got a middle-of-the-road scan tool (autoxray). Will that tell me about the bus?

is it a 4.7 ?
does it run when the 'no bus' fault is active ?

if both the above, put a crank sensor in it

This is the 2000 Durango you just got, right?
Gotta have an OBDII scanner.
Yes, it's the 'network' for all the computers in the car. They have 2 networks now, the CCD and SCI.
You will know more once you get a good battery in it and see if you can get any more codes.
Read the beginning of the BCM book on communication, and in the service manual. It will help.
IF there are any other tips like the one about the crank sensor, those are often easier than trying to diagnose it. IATN is good for common faults.
Do clean all connections that have been sprayed. Rusty coolant tends to make real nice connections where ther eshouldn't be!
Also clean all computer connections.

The CCD bus is the comunication system between all the cars or trucks controllers. It makes for alot less wiring. Its like if the speed sensor is picked up by the TCM (trans controller) it can be bussed out and every other controller on the car now knows the vehicle speed so you dont have to hard wire each controller that needs to know speed. Thats why alot of newer trucks may have the oil pressure sensor monitered by the PCM and then the oil pressure is bussed to the cluster and so on. Its best to put a DRB on it because if it says No Bus the DRB will tell you if its a short or a short to battery or an open or what ever because if the bus is down the DRB will usually say why its down but of course it wont tell you what the problem is. There are some comon problems but I have had all kind of weird bus problems over the years. Good luck , Ron

Yes, it's the 2000 Durango. It's got a 5.9. This is the wrong time of year to get something new to tinker on. Not much light left when I get home from work.....

My scan tool does work with OBDII.

Ok, I got a good battery in there and cranked, no start. Dash reads "no bus", scan tool says no communication. All the dash lights light up when you turn the key to on, but the fuel gauge and voltmeter don't move. I checked continuity of the bus between the engine computer and CTM and it was good. I don't like how shallow the pins fit on the instrument cluster, but it looks like there is contact.

The connectors don't look real good at the engine computer and I'd still like to replace the underhood harness, but my junkyarding today turned up nothing. The odometer does flash a few times when you cycle the key on-off-on-off-on and then displays the no bus. The radio does work and so do the power windows and locks.

The Mopar DRB scanner will tell you more but I always like to take my Fluke meter and measure the voltage of the plus and minus bus circuits and see if its shorted to ground or shorted to volts which is easy to see. Could also have an open somehwere and if at the controller that bias's the volts it will be a dead bus. Some CCD vehicle's have 2 controllers that bias the bus. You can also try unhooking controllers one at a time to see if one is taking the bus down. I had some trucks but I dont remember what years that got water in the ABS controller conector so you may also want to check that. Ron

I went over to the Durango/Dakota forums and fouind an interesting thread about "no bus". It did mention the 5v reference and checking it (the task for tomorrow), but pointed me back to something I needed to check anyway. Shortly before this problem started the shop replaced the transmission. There's a very real chance that they damaged the crank sensor or the wiring to it.......How about the speed/distance sensor?

If they pinched the crank sensor harness and shorted the 5 volt reference to ground you usually wont be able to comunicate with the PCM. Just turn the key on and unplug the MAP or TPS and check for the 5 volts. If it shorts to ground it will pull the whole circuit down. But you also have to watch as some PCM's have two 5 volt reference circuits. Ron

Ron, yes I have 5v at the TPS. I wound up helping an old neighbor with her car this afternoon so my stuff took a back seat for the day. I need to get better leads for my meter. Some of those connectors have small openings. I'll probably have time Thursday and Friday, but I'll get out there for a few minutes after work the next few days, too.

I'm also not ruling out the new computer taking a dump. I want to replace the underhood wiring harness due to the damage the previous owner did to the computer connectors. They go on, but they don't latch on and it appears that the pins aren't tight.