Takeuchi TB175 Wiring Issues and Troubleshooting

[MikePhua]

The Takeuchi TB175 is a compact hydraulic excavator known for its reliability and performance in various construction and landscaping tasks. However, like many machines, it can experience electrical issues that may affect its functionality. One common problem reported by operators is malfunctioning auxiliary hydraulics, including the thumb, two-speed tracks, and second auxiliary hydraulics. These issues are often linked to electrical faults, which can be challenging to diagnose without proper knowledge and tools.
Understanding the Electrical System
The TB175's electrical system is integral to its operation, controlling various components such as the auxiliary hydraulics, two-speed tracks, and other critical functions. The system relies on a network of fuses, relays, wiring harnesses, and sensors to ensure proper operation. A failure in any part of this network can lead to malfunctions or complete inoperability of certain functions.
Common Electrical Issues

1. Auxiliary Hydraulics Not Functioning: Operators have reported that the thumb and second auxiliary hydraulics do not operate as expected. In some cases, there is no hydraulic restriction when operating the thumb screw, indicating a lack of hydraulic flow. This issue can be caused by electrical problems, such as faulty solenoids, wiring issues, or problems with the control valves.
   
2. Two-Speed Tracks Not Engaging: Another common issue is the two-speed tracks failing to engage. Operators have noted that the "rabbit" light, which indicates high-speed mode, does not illuminate when the two-speed button is pressed. This could be due to electrical faults in the wiring or issues with the speed control solenoid.
   
3. Fuse Panel Failures: Some users have experienced complete failure of the left-side fuse panel, leading to the loss of functions like wipers, heater, and gauge cluster. This can be attributed to blown fuses, corrosion, or loose connections in the wiring harnesses.
   

Troubleshooting Steps
To diagnose and resolve electrical issues in the TB175, consider the following steps:

1. Inspect Fuses and Relays: Check all fuses and relays for continuity. Replace any that are blown or faulty. Ensure that the replacement fuses match the required amperage ratings to prevent further issues.
   
2. Examine Wiring Harnesses: Inspect the wiring harnesses for signs of wear, corrosion, or loose connections. Pay close attention to areas where the wires may be exposed to moisture or physical damage.
   
3. Test Solenoids and Control Valves: Use a multimeter to test the solenoids associated with the malfunctioning components. If a solenoid is not receiving the correct voltage, trace the wiring back to the source to identify any issues.
   
4. Check Sensors and Switches: Faulty sensors or switches can send incorrect signals to the control system, leading to malfunctions. Test these components for proper operation and replace them if necessary.
   
5. Consult the Wiring Diagram: Refer to the TB175's wiring diagram to understand the electrical layout and identify potential problem areas. This can help in tracing circuits and pinpointing faults.
   

Preventive Maintenance
To minimize the risk of electrical issues, regular maintenance is essential:

• Clean and Protect Connections: Regularly clean electrical connections and apply dielectric grease to prevent corrosion.
  
• Secure Wiring: Ensure that all wiring is securely fastened and protected from physical damage.
  
• Monitor Battery Voltage: Keep an eye on the battery voltage to ensure the electrical system is receiving adequate power.
  
• Schedule Regular Inspections: Conduct routine inspections of the electrical system to identify and address potential issues before they lead to failures.
  

Conclusion
Electrical issues in the Takeuchi TB175 can be complex and challenging to diagnose. However, by systematically inspecting the electrical components and following proper troubleshooting procedures, operators can identify and resolve these issues. Regular maintenance and vigilance are key to ensuring the longevity and reliability of the TB175's electrical system.