Inspection before measurement with a multimeter
A multimeter is a multifunctional and multi range measuring instrument that is indispensable in electronic and electrical technology. A general multimeter can measure DC current, DC voltage, AC current, AC voltage, resistance, and audio level, and some can also measure capacitance, inductance, and some parameters of semiconductors (such as β). If distinguished simply by display method, multimeters can be divided into pointer multimeters and digital multimeters.
The three basic functions of a multimeter are to measure resistance, voltage, and current, so the older generation called it a multimeter. Nowadays, multimeter has added many new functions, especially digital multimeter, such as measuring capacitance, transistor amplification, diode voltage drop, etc. There is also a talking digital multimeter that can broadcast measurement results in language.
Operation steps
Check whether the voltage and power generation of the battery are normal, and whether the battery pile head is severely rusted. Many car owners think that the leakage result is a battery problem or a generator problem;
Inquire with the car owner if there have been any recent repairs, additions, or collision disassembly activities;
Remove the negative pole of the battery, set the multimeter to the current range * high range, connect the red lead to the negative lead, and use the black lead
Connect the pen to the battery pile head and secure it;
Turn off all electrical appliances inside and outside the car, lock the doors, observe the current level, adjust to the appropriate gear, and record;
Wait for about 20 minutes; After all modules of the vehicle enter sleep mode, read the accurate static discharge current;
The static current is generally 0.03A (i.e. 30mA), please refer to the maintenance manual for details, and it should not exceed 50mA;
If the static current is too high, we can check it by pulling out the fuses and relays one by one, observing the magnitude of the static current;
Pre measurement inspection
Observe if the multimeter needle is set to 0. If it is not in the 0 position, turn the zero adjustment screw to set it to the 0 position.
Check the integrity of the two probes and leads. This is particularly crucial for measuring high AC voltages to prevent electric shock accidents.
Check the lead plug, and if there is any looseness, try to tighten it. Sometimes looseness is caused by the loosening of the fastening nut of the socket, and at this time, the watch case needs to be connected for repair.
