Enable Multimeters to Play a Greater Role in Maintenance
(1) Methods for leakage testing
When conducting a leakage test, a multimeter is required. The specific method is as follows: turn off all electrical equipment in the car, remove the ignition key, and use the accessory current clamp of the car multimeter. If the current flowing through the instrument is between 10-30mA, it indicates that the car has no leakage. On the contrary, if the display is too large, it is considered that there is a vehicle leakage fault. It should be noted that some systems absorb a significant amount of power within 15 minutes of turning off the ignition switch. Therefore, if the current is measured to be above 50mA, it should be tested again after 15 minutes. If it is still above 50mA at this time, it indicates that there is indeed a discharge phenomenon and further diagnosis is needed. After confirming that there is a leakage in the vehicle body, keep the current clamp firmly on the negative terminal of the battery. You can take out the fuses one by one while observing the changes in the instrument current value. If there is no change in the number displayed on the instrument after removing a certain fuse, it indicates that the leakage is not occurring in that circuit. If the value displayed on the digital clamp ammeter returns to normal 10-30mA (some cars have normal values below 50mA, depending on the model), it indicates that the leakage phenomenon has been eliminated, which means that there is a leakage, grounding or short circuit problem in the fuse control circuit.
(2) Quickly diagnose electrical equipment
By using the current testing function, it is also possible to quickly diagnose and detect the reasons why many electrical devices on the car, such as headlights, speakers, oil pump relays, electric door and window motors, and generators, are not working. For example, for the detection of electric fuel pumps, if the working current I=4.5A and the fuel pump is working normally, if there is a fuel cut-off phenomenon, it is caused by the circuit connection * *; If the working current I is less than 4.5A, it indicates that there is a resistor or connection in the circuit, or the oil tank is too dirty, impurities are blocked into the oil filter, and the oil pump cannot suction oil, forming a no-load current; If the working current I is greater than 4.5A, it indicates that the fuel filter may be clogged or partially clogged, causing an increase in the load on the fuel pump. In this case, misjudgment of the oil pump is highly likely to occur, and attention should be paid during testing.
