I would pull the headlamp relays and check the marker lights for moisture/shorts... After that you're probably looking for a shorted wire somewhere (which sucks).Apparently I am experiencing the notorious driving lights/dash lights/horn circuit gremlin. It started with the switch being a little quirky when I'd turn the lights on and the dash lights didn't immediately illuminate until I wiggled the light switch. Then this weekend they stopped operating at all, along with the parking lights, tail lights and horn. I first checked the 15 amp horn fuse (third from left on the top) and sure enough it was blown. Popped another one in there and as soon as I turned on the driving lights it blew again. So, I removed, disassembled and cleaned the combination switch from the steering column as per the instructions in this excellent tutorial: http://www.delica.ca/forum/viewtopic.php?f=98&t=11284
Unfortunately that didn't solve the problem and the circuit continued to blow fuses when I switched on the parking lights. I did test the horn to make sure it wasn't blowing the fuse. I hope I'm wrong but it seems likely that the switch is just worn out and somehow shorting and causing the fuse to blow. Any ideas or suggestions to troubleshoot and resolve this issue is greatly appreciated. Thanks.