Cougarman,
Have you used a volt-meter to see if voltage is present at the bulb socket? Also, use the voltmeter to check both sides of the fuse as sometimes they blow and it is hard to see with the eye but voltmeters don't lie.. Sometimes the contacts on the mount or the bulb itself may have corroded and need to be scraped off to insure good clean contact.
If the fuse is good and you do read voltage at the lamp socket, you evidently have a defective bulb. If you don't read voltage, run a temporary frame ground wire and re-check the voltage wire. After ensuring you have a good ground and there is still no voltage on the VM, you evidently have an open in the hot wire. If there is voltage at the bulb socket, then you have an open ground wire. Usually if there is an open in the battery or ground wires, it will be somewhere in the wire run. Check the lamp that is closest to your fuse board first. You may have to check the wiring behind the socket to see if either is open. The lights are usually pigtailed off a common wire run.
If you have an owners manual, check the wiring schematic that shows how the wires are run in your particular model. Our Hi Lo has a left side and a right side run. I believe it is the right side [road side] that feeds the bathroom light and vent fan. Hope this helps.
Jerry Curtis
2406 T