Electrical Boot Camp · Module 01
Follow the voltage from the battery to the load and catch where it falls off a cliff.
Module 00 measured the drop across one suspect connection. The available-voltage test zooms out: with the load running, you measure the voltage to ground at each point as you walk down the circuit — battery, fuse, switch, connector, load. A healthy circuit barely loses any voltage along the way, so every point reads close to source. The moment the number takes a big step down, the fault is the piece you just crossed.
Black lead on a known-good ground. Red lead hops from point to point toward the load. Voltage stays high, then cliffs at one spot. The bad connection is between the last good reading and the first low one.
The load has to be on and drawing current, or there's no drop to see — an open-load circuit reads full voltage everywhere and hides the fault. Same principle as Module 00: V = I × R, and with no I there's no clue.
A blower motor fed through three connectors. Put a fault on one and watch the voltage staircase cliff.
Reason first, then reveal.
ASE-style. Pick an answer to see why.