Small excavator is relatively compact in terms of parts arrangement and circuit due to small space. Therefore, some failures are unavoidable. When the horn fuse of the excavator blows frequently and the machine cannot be started. After forcibly starting the excavator, it was found that the machine not only did not move, but also could not add the accelerator. This article will analyze and explain this fault for reference only.
1. Fault analysis
The maintenance personnel shall follow the fault phenomenon and combine the past maintenance experience. Preliminary analysis shows that the above faults are caused by circuit. Specifically, check the harness problem, main controller fault and GPS fault.
2. Troubleshooting process
First, check each harness connector according to the analysis. No signs of disassembly and looseness are found. Check the harness with a multimeter and find that the 23 # wire related to the horn, indoor lamp and standby lamp power supply is short circuited. Further inspection found that the insulation at the connection between the indoor lamp harness and the cab floor was damaged. Start the excavator after replacing new parts, and the horn works normally. However, the machine still cannot be started. Secondly, when the key switch is turned to “START” position, K3 does not pull in. Check that the channel is from the 62 # line at the output end of the master controller to the 62 # line at the K3 end. However, Line 62 # at the controller end has no power. The fault phenomenon remains unchanged after replacing the main controller with a new one. This eliminates the main controller problem. Moreover, restore the circuit. The GPS signal lamp flashes abnormally. Dismantle the bottom plate at the lower part of the cab and find a bundle of wires twisted together. After the harness is re fixed, especially after the harnesses at the rear of the seat are re fixed with ties, the GPS signal returns to normal, the machine starts to normal, and the throttle control and action return to normal. From this, it can be determined that the cause of the fault is due to poor contact of the harness.
Small excavator has a very compact structure when leaving the factory. Especially the harness. If the fixing is not firm and the machine is working, high frequency vibration will occur. It is easy to cause the harness to be twisted and loose, and finally lead to poor contact, so the machine cannot work normally.
