Method for Checking the Resistance of Pull-in and Holding Coils in Electromagnetic Switches with a Multimeter
The working current of the starter motor is high and the speed is high. In order to ensure the normal operation of the starter motor, the car starting system should be used correctly; Due to some inappropriate operations, malfunctions will always occur, such as:
When the starting system malfunctions, the starter motor is often the most susceptible component to failure. In the start-up system, due to the complexity of system components and the reliability of the control system, the requirements for motor performance are very important. Therefore, the starting motor plays a very important role in the starting system. When analyzing the faults of the starting system, sufficient attention must be paid to the analysis of the starting motor. Below is one of the points - checking the working condition of the electromagnetic switch on board the vehicle. The main steps can be followed:
1. Check the resistance of the electromagnetic switch attraction coil
Select the multimeter in the ohm range, and connect the two probes to terminal 2 and terminal 3 of the electromagnetic switch respectively. The negative value is generally 0.5~1.0 Ω. If the resistance value is infinite, it indicates that the attraction coil is disconnected. When the ignition switch is rotated to the start position, the electromagnetic switch does not have any action; If the resistance value is too small, it indicates that there is a short circuit between the turns of the attraction coil. When the ignition switch is rotated to the start position, the electromagnetic switch has a weak action, emitting a weak "click, click, click" sound, and the driving gear has no action.
2. Check the resistance of the electromagnetic switch holding coil
Select the multimeter in the ohm range, and connect the two probes to the three terminals of the electromagnetic switch and the electromagnetic switch housing respectively. The resistance value is generally 1.0~1.5 Ω. If the resistance value is infinite, it indicates that the coil is kept open circuit; If the resistance value is too small, it indicates that the coil turns are short circuited. Whether keeping the coil open or the inter turn short circuit, the electromagnetic switch will make repeated "click, click, click" sounds, and the driving gear will not move. The only difference is that the frequency of the sound produced by a turn to turn short circuit is lower than that after a circuit break.
