I know this may NOT be a Workhorse issue. But, it may be?
My front and back side marker lights don't always work. If I tap the ICC switch they will work at times. The only other system failure, with my lights on, is my control cluster (speedometer) -- it also works intermittently. I guess the only solution is to drive during the day!
I pulled the ICC switch and found a melting

14 gauge brown wire attached to ICC Carlingswitch V3D1 which is attached to Hamsar 43018 Electronic Flasher J590 & J945. The burnout is next to the ICC post.
NOTE: I'm stupid when it comes to electrical issues.

The ICC switch has 20A printed on the side and the Hamsar has a DOT warning that input lead must be 25 amp fused. Maybe one of you electrical guru's can help me out. Would an inline 20A fuse stop the wire melting?
Tokruys: Where did you find the new switch?
Did this solve your problem?
Workhorse CC 2003 Damon Daybreak