Trouble phenomenon:
The wires between the main controller (MC), EC motor, and engine controller are faulty. Even if the engine controller rotates, the engine speed does not change.
Fault diagnosis and troubleshooting steps:
(1) Diagnose with the Dr.EX diagnostic analyzer, check whether the fault code 07 is displayed on the screen (07 means the engine controller is faulty). If fault code 07 is displayed, it means that the engine controller is faulty. The engine controller connector should be disconnected, and the resistance between terminals 5 and 7 on the engine controller side should be checked whether the resistance is (5±0.5)k, and then the engine The controller is connected, insert the test needle of the multimeter from the back of the engine controller, and turn the engine controller to check the voltage change. Does the voltage reach 0.3~1.0V at the lowest speed position? Is the voltage at the highest speed position? Reach 40~4.7V? If the resistance and voltage do not meet the requirements, it means that the engine controller is faulty, and the fault can be eliminated after replacement.
(2) If the detected resistance and voltage are within the specified range, but the fault still exists, disconnect the engine controller connector, and check whether the voltage between the terminal 5 and 7 of the wire end connector is (5±0.5) V (The key switch is in the ON position). If the voltage is abnormal, continue to check whether the voltage between the terminal 5 of the wire end connector and the chassis is (5 ± 0.5) V (the key switch is in the ON position). If the voltage is still abnormal, it means that the main controller and engine control The wire between terminal 5 of the engine is open. After repair or replacement, the fault can be eliminated; if the voltage is normal, it means that the wire between the main controller and terminal 7 of the engine controller is open. After repair or replacement, the fault can be eliminated.
(3) If the voltage between the terminal 5 and 7 of the wire end connector is within the range of (5±0.5) V (the key switch is in the ON position), continue to check the main controller 22P connector terminal D21 and the engine controller terminal 6 Whether there is an open circuit or short circuit between them. If there is no open circuit or short circuit, it means that the main controller is faulty (note: engine speed adjustment and engine learning are required after replacing the main controller); if there is open circuit or short circuit, carry out related excavator maintenance
(4) If the fault code 07 is not displayed on the screen when the Dr.EX diagnostic analyzer is used for diagnosis, the light wire (part number is ST725) should be connected. Connect the lighted wire components between the connectors, and check whether the circuit is always constant according to whether the light is on or off during the operation) Connect to the EC motor, when the engine controller is rotating, check whether the light is on, if the light is not on , It means that the main controller is faulty or the wire between the main controller and the EC motor is disconnected: if the light is on, it means that the EC motor is faulty.
