levigideon wrote: Today it happened again, but after I shut everything off, my dash lights all stayed on, no matter what I did with the headlight switch.
No fuse is going to power the dash lights when the switch is off. This is likely a failure in the headlight switch.
If you are careful you can pry back the folded metal tabs that close the switch to hold the parts in. Have a care as you may only get one chance. Bending these tabs more than once may snap them off. You can take out the sliding parts and the brass contacts and clean them. May even be something in there that's broken like a spring.
To remove the switch unplug it first. Pull switch out fully. Grip the brass stem tightly with needle nose pliers and at the same time push inward on the knob and turn to release it. Now loosen the nut on the front of the dash and push the switch through and retrieve.
A short is a path around a load to ground and would either blow a fuse, which is what they are supposed to do, or melt a wire starting a fire. An open (or bad) connection would cause the lights to go out. This could be a dirty or worn contact, often intermittent. The dash lights staying on could be something loose/broken inside the switch making contact where it should not. This would not be a short strictly speaking.
The lights going out could also be a poor fuse contact that heats up and 'opens'. So replace the headlight fuse and check the fuse clips are clean and grip the fuse securely. As stated this won't cause the lights to stay on. Likely both problems are in the switch.
My Datsuns, like good friends, have never let me down. At least in any way that was not understandable and thus fixable.