The other thread posted above has some good ideas, but it is not the system in your 2002 coach.
Here is the troubleshooting info for your system:
http://www.discoveryowners.com/VDCTR...OTINGGUIDE.pdf
I would try to find the connector that connects to the message center, and reseat that one. The 2 data lines and + and - wires from the VDC go to the message center. From the message center, a spider harness drives the individual instruments.
You can also get some free advice from the Freightliner help Desk (free service). Have your VIN number available when you call. 1 800 FTL HELP
Fred