Attempting to measure current across a voltage source is a very common mistake that people make; even old hands might occasionally make that mistake. Welcome to the charred component club; I'll bet you won't forget that lesson.

Voltage is measured in parallel with the source, or on a component.

Current is measured in series with the load.

A more safe way of measuring current is indirectly, by using a precision resistor in series with the load, and measuring the voltage drop across the resistor.

If the resistor measures 1 Ohm, then a voltage drop of 1v across the resistor is 1A current through the resistor. I=E/R

Wise counsel

 

I ran into the intermittant fuse TWICE. it checked with an ohmmeter just fine. When you tried to pass current through it, it opened. Annoying.

I hate when that happens.

Had a 72 Chevy Nova with a left headlight that was burned out - barely. Yes, barely burned out. I could roll down the window and reach out and wrap on the fender and the light would come on. Friends called me "The Fonz!". The vibrations from wrapping on the fender would cause the filaments to touch and light. Once lit the filament would weld itself back together, only to break when you shut the lights off. Funny, I remember that headlight giving me months of service that way before it just wouldn't light anymore.

 

I had the blinking headlights syndrome in a 1965 Ford, about every 30s. One lamp failed shorted. The breaker was a self-resetting thermal breaker. A later Japanese car I owned had a fuse for each low and high beam.

The J car had flip up headlights and the wires broke. Replaced them with Test probe wire.

 

This reminds me of the science project of a classmate of my son. The two boys had been working on their projects at his friend's house with his dad helping out. When I came to pick up my son, the other dad asked me if I could figure out what was going on with his lamp circuit. It seemed to work a little backward, when the switch was set to ON, the lamp turned off but when set to OFF, the lamp turned on. The next question he asked told me all I needed to know: Why do the wires get hot when I turn the lamp off?

His switch was across the battery terminals and would short the battery when closed.