![]() ![]() ![]() As the internal temperature of the automatic gearbox rises, the surface temperature of the solenoid valve will rise as well, resulting in changes of the initial fit clearance. That heat makes something expand and cold makes it contract has been a common sense. If the actually-measured value under the hot state is larger than the resistance difference, it means that the heat stability of the solenoid valve is poor. This can ensure perfectly safe.Įxperimental results suggest the resistance value of the general electronic valve at the cold state and the hot state differs by around three to five ohms. During the process of test, one resistance of dozens of ohms is connected with the electric appliance loop of the pressure-regulating solenoid valve to limit the current flowing through the solenoid valve. If the 12V power is directly added thereto, the solenoid valve damage might be easily caused. The resistance value of the pressure-regulating solenoid valve is generally small. Of special note is that, before power-up test, characteristics and type of the solenoid valve should be clarified to see which is a gear-shift solenoid valve and which is a pressure-regulating solenoid valve. Results of the above three inspections all suggest that the inside of the solenoid valve has been seriously worn-out and must be fully changed in the maintenance process. If the results are abnormal, the solenoid valve should be changed to a new one without hesitation. If the test results are normal, it means that solenoid valve has no problems. Then, conduct the resistance and dynamic pressure test. Heat the solenoid valve artificially using the air heater or other oil-powered or electric heating equipment to the normal working temperature. Thermal inspection refers to the set temperature which can be reached when simulating the normal operation of the automatic gearbox. The maintenance process might be stuck in different faults. A large number of maintenance examples have proved that, even if the solenoid valve passes the above two inspections, it might be abnormal and less satisfactory when entering the thermal working status. The above two inspections cannot address problems by 100%. Thermal inspection of the automatic transmission solenoid valve All the above states can suggest the solenoid valve has become invalid and must be changed for a new one. If it is infinitely large, it means the solenoid valve coil is in an open-circuit status. When it is lower than the rated value, it means the solenoid valve coil interturn suffers short circuit. When the resistance value is higher than the rated value, it means the solenoid valve coil has been aging. Static inspection of the solenoid valve refers to measurement of the solenoid valve resistance value and connection of the multimeter pen point with the solenoid valve contact pin to observe the resistance value on the instrument screen when the ignition switch is off. Static inspection of the automatic transmission solenoid valve In the following part, let's us introduce 3 effective inspection methods for the automatic transmission solenoid valve. Meanwhile, inspection of the solenoid valve is also an indispensable link in the maintenance process of the automatic gearbox. The working state of the solenoid valve can directly influence the working status of the automatic gearbox. Different solenoid valve states are corresponding to different gears. The solenoid valve is an important actuating element to ensure normal operation of the automatic transmission. The solenoid valve in the automatic transmission is equal to the actuator, whose main function is to control the mechanical valve to finish the oil circuit exchange and the oil circuit flow control of the mechanical valve (pressure regulation). ![]()
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