All, I have a issue 1992 U225 Cummins 5.9 upper cabinet, drivers side fan. The fan is 4 wire, yellow low spd, orange high spd, red medium spd, black is ground. FT connections, yellow, orange and black. I know that I have 13v with ignition on yellow wire with the fan swt in either position. I have no voltage on orange with the fan switch in either selection position. With ing swt off, no power on org or yellow wire. Any ideas on the correct connection. Thanks all.