It is difficult to find out the cause of excavator circuit failure. Each small component may lead to the paralysis of the whole system. The best way to check the circuit problem is to check the circuit diagram, understand the circuit operation route of the whole vehicle through the circuit diagram, so as to narrow the fault scope, and finally lock and solve the fault through actual troubleshooting. For an excavator working for more than 9000 hours, the driver has the fault that the display screen is always on and the excavator cannot be powered off after the engine is shut down. This article will take this as an example to explain how to check and solve such a fault, which is only for reference.
1. Cause analysis
The maintenance personnel compared the circuit schematic diagram of the excavator to diagnose the fault causes in the following aspects:
1) The excavator cannot be powered off due to the failure of excavator battery relay
2) The failure of the harness of the battery leads to the failure that the power cannot be cut off
3) The excavator cannot be powered off due to the damage of the starting key switch of the excavator
4) Excavator computer board failure
2. Troubleshooting and handling
1) The maintenance personnel found that when the key switch was turned to off, the excavator could shut down. However, the display screen is always on and does not go out, and the battery relay will not have a disconnected ticking sound.
2) Use a multimeter to measure the signal control line 13 on the battery, with 24V voltage input. After the signal line is removed with a screwdriver, the excavator is powered off and the battery relay fault is eliminated.
3) Check the key switch and measure the output of line 13 when it is turned to off. No output, remove the key switch fault.
4) Then compare the circuit diagram and run along the circuit to check the circuit. It was found that a diode on the line was broken down, resulting in the failure of the excavator to power off in time.
5) Replace the damaged and broken diode and restart it. The equipment returns to normal, and the excavator can be powered on and off normally.
The maintenance personnel told to keep the inside of the battery box clean to prevent the components from being damaged by water. Never connect electrical appliances without permission. Increasing the power load will lead to excessive current and burn electrical components, resulting in circuit failure. When dealing with the fault of the electrical system, there is no need for heavy operation, large disassembly and large unloading. The possible causes and judgment standards of the fault must be judged in principle in advance. Therefore, it is very important to learn to view and understand the circuit schematic diagram, and then measure and diagnose with the help of tools to accurately judge the fault location and cause.
