A lot of Freightliner Chassis have what's called EL lighting in the dash. An EL inverter to convert the 12 VDC to 100 VAC or more (very low current) is used and they sometimes go bad just like Florescent Light Ballasts.
Call The Freightliner Hot Line 1-800-FTL-HELP and see if they will send you the specs. Buying from them will cost way too much and these things are for sale on the web. The hard thing will be finding it.
1999 Tradewinds 7372 Cat 3126