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Dash lights cause fuse to blow.

Posted October 21, 201410 yr

Good evening all,

I've searched through the forum, but can't find a similar issue to mine, so here it goes.

I've got a 1975 280z, and I'm trying to hunt down an issue that's keeping me from having dash lights. I can turn the headlights on, including the brights, but as soon as I turn the dial for the dash dimmer the wire in the rheostat burns up. If I turn it to the brightest setting (doesn't use rheostat wires, just straight contacts) a few dash lights come on, then the fuse glows red-hot and blows. The wires to the rheostat get pretty hot too, as does the combo switch. The car is all stock electrically, and I've hooked up a test light and there aren't any shorts I can see.

I've started testing the combination switch, since it's getting warm even with the dash lights off, and found that the green/white wire has continuity to the white/red and solid red wires, and all also have continuity to the metal body of the combo switch. I disconnected the switch and tested it, and no continuity on those points, it's just in the wiring harness itself. White/red and red have continuity prior to the switch, something along the lines of 4-5Kohms. Should these wires have continuity, and what might be my issue? I've checked the car's schematic in a manual I have, and ensured all bulbs are the correct wattage as well. This issue is driving me mad!

On a side note, my passenger front combination turn/marker light has a corroded socket, but that wouldn't be enough to cause such an issue, could it? Any help is greatly appreciated, I've posted on Ratsun, but no one has responded yet with a solid answer.