Headlights

I have a 94 cherokee, about a month ago the lights went out. I replaced the headlight switch, and that fixed it. Last night the tail lights went out. Replaced the fuse and that fixed the problem. Now the headlights went out again, I replaced the switch but that didn't fix it. Any suggestions??
And the headlights work if I hold the bright lever in.

http://www.autozone.com/az/cds/en_us/0900823d/80/15/3e/8f/0900823d80153e8f/repairInfoPages.htm

Use Fig. 36 and 43, I know the years are different, but close enough.

Troubleshoot from the top of schematics.