Meter Settings and Safe Use
DC Volts. Red to test point. Black to ground.
Meter Settings and Safe Use
Set to DC Volts. Red lead to positive. Black to COM/ground.
A digital multimeter used on the wrong setting produces incorrect readings. On a high-current circuit it can destroy the meter in an instant. Understanding the settings is not optional — it is safety and accuracy at the same time.
DC Voltage — your primary setting
Set to DC volts for measuring battery voltage, circuit voltage at any point, sensor output signals, and module control signals. Most automotive circuits operate on DC voltage. Set to DC voltage before probing any live circuit on the vehicle. Red probe to the point being tested, black probe to a known good ground.
Resistance — Ohms
The circuit must be completely unpowered before you test resistance. Battery disconnected or circuit fully de-energized. Testing resistance on a powered circuit does not give you useful readings. Zero ohms means a good conductor with no measurable resistance. OL or infinite means an open circuit — no current path exists.
DC Amperage — the one that destroys meters
Standard ammeter testing requires the meter to be connected in series with the circuit — the current must flow through the meter. You must use the correct amperage input jack on the meter. If you connect the amp input jack and then try to measure voltage, you will blow the meter's internal fuse instantly. For any high current measurement, use a clamp-on amp probe around the wire instead — no circuit interruption required, no risk to the meter.