Mine do not work even with the lights on. Does the headlight washer share a common pump with the windshield washer or is there a water line that could be loose or broken? (1990 LJ78)
I was never able to make mine work either. I tried everything. On the 78 the headlight bottle and pump are seprate from the wiper washer bottle and the pump. The headlight bottle and pump is behind the first battery on the left fender. The oddest part is that the head light bottle is 3 times the size of the wiper washer bottle. Anyways the head light washer set up got tossed and my winch solenoid pack and plug took it's place. You can power the motor and see if it works then start tracing the problem.
On my 1990 LJ78 there is fluid in the bottle and all of the plumbing is intact however it does not spray the headlights. I assume the actual pump is the problem and I have to weigh the expense of replacing the pump versus occasionally having dirty headlights. ...............1978HJ45
The 80-series have a dedicated switch for the headlight washer. Switch on the lights, then you get a 1 second spray with each push of the button. Perhaps you could find the washer switch from a non-North American 80-series. Or any momentary switch will work. Wire it up with a relay energized by the headlights.