its the flasher switch most likely, or the wiring to it. all the power from the lights comes via the flasher switch. you know fuses are ok as the lights flash fine, the problem is you have lost power feed to the wiper stalk. it might be relay #18 is loose tho, give it a wiggle.
no relay for the lights as such, but the 18 relay supplies lots of stuff in the car with ignition live, the lights included.
check the white/black wire to the stalks to pin 3 on the plug gets power when the light switch is on the 2nd click. if you dont get power here, you have a damaged wire or the headlight switch is bust. check for power at the white/black wire to the headlight switch, this is at pin 58 on the switch. if you get power here, then light switch is fine, follow the wiring back and check for faults.