After doing a lot of reading on bus errors in Chrysler models, I've found that Chrysler did a lot of changing/upgrading between the 1980s when the CCD (Chrysler Collision Detection) bus was introduced and 2005, when most models were switched to the CAN (Controller Area Network) bus system. In between those two, from 2001 through 2004 for most models, they used the PCI (Programmable Communication Interface) bus system.
With the older CCD bus system, apparently many NOBUS errors could be corrected by changing the crank position sensor
, as it was one of the signals carried by the bus. Or it could be corrected by changing the PCM or instrument cluster.
For the PCI system, ALL controllers with microprocessors (PCM, TCM, BCM, instrument cluster, anti-lock brake controller
, air bag controller, keyless entry
, sound system, etc) are linked to the PCI bus. So a NOBUS error message in the odometer only says that there is a communication fault in the bus; it can't tell you which module/microprocessor is not working properly or if it's a wiring error. Changing out the PCM may correct the problem since the PCM is the 'dominant' module, but no guarantees.
Reading forums and other web sites regarding this issue, the prevailing advice is to use a DRB scanner capable of communicating with the different modules to see if they are all communicating properly. But it seems that the fault most often lies in a poor ground connection or damaged wiring or connectors.
If your local mechanics are stumped, find one (or go to a dealer) who can do troubleshooting of all modules with appropriate scanners. It may be a quick fix, but you'll have to invest in the expertise of someone who knows what to look for and how to diagnose it.