89 k5 blazer head lights dont work?.

[89k5350]

i have a 89 k5 blazer all stock with a 350. my headlights did not work when i got it and still dont. it has been a plow truck most of its life so the head lights might have been wired to some other lights. two plowing lights did come with it but werent hooked up or anything.when i pull the head light knob only the dash lights and flashers come on. any one have an idea whats wrong? let me know what i could do.

 

[K85 Octane]

best advice
get a shop manual and start chasing wires, like the ones at the headlights, also the fuse. Check grounds on the core support and such. Someone may have molested it in the past.