BCM/CCD BUS problem with 2000 caravan.
Your problem is not uncommon. It's usually caused by a single source. But first, an explanation of the system. To save wiring weight and complexity, the factory decided to use a communication bus network to save on both. The bus system, the CCD, connects practically every system on your vehicle through something not unlike the Internet.
By not having to use individual wires to move information, it was designed to simplify matters. But when it goes down, it can pretty much take everybody with it.
Your instrument cluster uses information primarily from the Powertrain Control Module (PCM). That's the engine controller. All gauge functions come from that location. Other inputs, such as low washer fluid, come from the body control module (BCM), which is definitely on the bus network.
A good diagnosis of the system under ideal conditions (stuff broke) would involve a scan of bus voltages and then a systematic disconnection of each module, looking for a return to normal operation.
Barring the opportunity to see a system when it's actually broken (normal for me) is to use the forensic approach.
Scan each and every system on the bus network on the vehicle. Most have memories that allow codes to be set when problems exist (or had existed).
Typically, the one system that has absolutely no idea anything had happened (no codes) will be the one that caused the problems.
Overwhelmingly, this turns out to be the instrument cluster printed circuit board. It isn't the cluster itself, but rather the board that screws to the back side of the cluster. It contains a rather large array of ICs and does more than just shuttle voltage from one spot to another.
The cluster is one of two sources for CCD bus voltage and termination. Voltage, we understand. It runs two 2.5 volt circuits (designated + and -), which connect all systems.
Equally important, it also provides the return circuit, termination. When this circuit fails, the bus voltage takes off, running about 5v above normal. For a bus system that runs only 2.5 volts, this turns 10101001 into 11111111. Effectively...zip.
OK, more than you needed. I might have an easy tip for diagnosis. It may work, which would be nice. If it doesn't work, it isn't conclusive.
When the cluster is acting up, deliver a medium-hard (open palm) slap to the instrument panel area of the dash, directly above. Maybe three. It should return cluster operation to normal and is a positive diagnosis to the cause of your problem.
It doesn't seem terribly technical or scientific. But that's the beauty. If you disconnect the cluster, you can't see a change (it's disconnected, for Pete's sake). You would need a factory scan tool to see the difference, and that's probably not an option. Slapping the cluster and seeing an immediate change is as good as it gets in this case.
If this turns out to be your problem, you will need to see the dealer in any case. The replacement board must be calibrated using the factory scan tool. It will not display tachometer or speedometer readings until done. So even if you put the part in, it will still need to be touched by a Dodge technician to make it work.
While the bus is down, functions from the BCM won't make its way to the cluster either. That might account for the lack of dash lights and such.
I realize this is terribly general and based on past experience and probability with your vehicle. The best diagnosis is to do a vehicle scan and go from there. That's barring the calibrated dash slap, of course.
