Checks performed before multimeter measurements
Multimeter is a multifunctional, multi-range measurement instrument, electronic and electrical technology is always inseparable from it. General multimeter can measure DC current, DC voltage, AC current, AC voltage, resistance and audio level, some can also measure capacitance, inductance and semiconductor parameters (such as β) and so on. If the display is simply distinguished, the multimeter can be divided into pointer multimeter and digital multimeter.
The three basic functions of a multimeter are to measure resistance, voltage and current, so the old-timers called it a triple meter. Nowadays, the multimeter has added many new functions, especially the digital multimeter, such as measuring capacitance, transistor amplification, diode voltage drop, etc. There is a kind of digital multimeter that can speak, which can broadcast the measurement results in language.
Operation steps
Check whether the battery voltage and power generation is normal and whether the battery stake head is rusted seriously, many owners think that the leakage results in battery problems, or generator problems;
Ask the owner, recently there is no repair what, add what or collision dismantle where;
Remove the negative terminal of the battery, set the multimeter to the maximum current gear, the red pen connects the negative level wire, the black pen connects the battery stake head and fixed;
Turn off all electrical appliances inside and outside the vehicle, lock the doors, observe the current size, adjust to the appropriate gear, record;
Wait for about 20 minutes; read the accurate static discharge current after all modules of the vehicle have entered the dormant state;
The static current is generally at 0.03A (i.e. 30mA), refer to the service manual for details, not more than 50mA;
If the static current is too large, we can check it by pulling out the insurance and relay, i.e. pull out the insurance one by one and observe the size of the static current;
Check before measurement
Observe whether the multimeter needle is set at 0. If it is not at 0, rotate the zeroing screw to make it set at 0.
Check the integrity of the two pens and leads. This is especially critical when measuring higher AC voltages to prevent electrocution.
Check the lead plugs and try to tighten them if they are loose. Sometimes the looseness is caused by the jack's fastening nut loosening, this time to play and case to repair.
