Multimeter

It is the basic tool for checking batteries, fuses, sensors and wiring. Digital meters show values on a screen; many also test diodes and continuity. Current measurement needs the meter in series and the correct socket. Auto-ranging meters are easier to use; minimum and maximum capture help with intermittent faults. Current clamps measure current without breaking the circuit.

Probes are placed across or in series with the part and the meter displays the measured value.

Measuring resistance on a powered circuit can give false readings or damage the meter. Use a meter rated for automotive use; high-voltage systems need special rated equipment.