Rear side marker lights blows headlight relay fuse and vice versa

Hi everyone:

I have my headlights on a 5 pin relay with 87 +12v battery (with a 10A fuse on each), 30 output to LB/HB, 86 headlight on/off switch, and 85 ground to LB/HB dimmer. I noticed my rear side passenger marker light was out so I replaced it. But when I switch on the headlights it blows the 10A HB fuse. However if I replace the 10A fuse and put back in the burned out bulb into the rear side passenger marker light socket I don't blow the headlight 10A fuse when switching between hi/low beam.

Don't the running lights route through the hazard switch and the headlights through the combo switch? I don't how how the headlight and running light would short/open one another?

Howard

1974 260z

Edited June 9, 20177 yr by 882993md