Headlight Switch Cranks Engine??
My trunk and Interior dome lights since I got the car always stayed on when I put a fused in then after 30 seconds, the fuse begins too cook itself.
Which means there is a short either between wires or to ground.
If its that bad, it can be found by following the wires and the method to use instead of looking for voltage drops would be checking continuity or resistance.
These are testing methods done with the battery disconnected.
The way to avoid going crazy looking at the wiring diagrams while working on the car is as follows:
Take the diagrams and trace or sketch just the circuit you are working on.
It may take two attempts but it will make everything much easier to follow.
There is problem with starting - draw the wires and connections for just that circuit.
Same with dome light.
Same with parking and turn signals. This can be one of the more difficult circuits, really two circuits. Having the markers on the fender makes just a little more confusing. Draw it out. Trace in real life, adjust your drawing as needed, put notes on it, whatever you need to keep track of what you've done and found.