How do I measure current safely with a multimeter?
Short answer: Move the red lead to the amps jack, break the circuit and put the meter in series, start on the highest range, and never connect the meter across a voltage source in amps mode.
Measuring current is the one test that can damage a meter or blow its fuse quickly. In amps mode the meter has almost no resistance, so connecting it across battery terminals or a powered circuit creates a short.
The safe way is to open the circuit, often by removing a fuse or disconnecting a terminal, and connect the meter in series so all the current flows through it. Start on the 10 amp range and check the meter's limit, since many 10 amp inputs are rated only for short periods. Do not try to measure starter or high-current draws through the meter.
For anything above a few amps, or when you do not want to break the circuit, use a clamp-on current probe. It reads current through the wire without opening it, works with a meter or scope, and is much safer for both you and the meter. Move the lead back to the volts jack when you finish.
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General guidance only. Follow the vehicle and tool manufacturer's procedures, and confirm vehicle coverage on the tool maker's list before buying.