ASV Equipment Blowing Fuses: Causes and Solutions

[MikePhua]

Issue Description
In ASV equipment such as the VT70 model, a common electrical problem observed is blowing of the starter fuse—a small 10 amp red fuse—when the cab is lifted. The fuse blows repeatedly and seems correlated with the cab position. An investigation revealed rubbing wires under the cab’s lifting section, which after temporary repair allowed the machine to operate again until the fuse blew once more.
Root Causes

• Wiring Harness Damage: Repeated lifting and lowering of the cab can cause wires to rub against sharp edges or moving parts, leading to insulation wear, shorts, or exposed wiring.
  
• Loose or Damaged Connectors: Moisture ingress or mechanical strain can cause connectors to lose integrity causing intermittent short circuits.
  
• Fuse Rating and System Load: Using a fuse with an incorrect rating or a sudden high load current from faulty wiring or components can cause repeated fuse blowing.
  
• Harness Routing and Protection Issues: Insufficient protection (e.g., lack of conduit or proper cable clamps) allows wires to move freely and contact metal surfaces.
  

Diagnosis and Repair

• Conduct a thorough visual inspection of wiring around the cab lift mechanism and drive unit, focusing on areas with visible wear or rubbing.
  
• Use electrical contact cleaner on connectors to remove corrosion, and apply dielectric grease to prevent moisture intrusion.
  
• Secure wiring harnesses with proper clamps or conduit to minimize movement and rubbing.
  
• Replace damaged or frayed wires and connectors as necessary.
  
• Ensure the fuse is the correct specification for the circuit—overrating a fuse risks damage, underrating causes nuisance blowing.
  
• Test with cab in multiple positions to confirm that no wire is shorting during normal operation.
  

Preventative Measures

• Regularly inspect wiring during routine maintenance checks, especially in areas where the cab or other moving structures flex the harness.
  
• Add protective coverings or sleeves over wiring bundles in problematic areas.
  
• Train operators and service personnel to recognize symptoms of electrical wear such as intermittent power loss or repetitive fuse blowing.
  

Terminology

• Fuse: Safety device protecting wiring and components by breaking the circuit under excess current.
  
• Wiring Harness: Bundle of electrical wires transmitting power and signals throughout the machine.
  
• Dielectric Grease: Non-conductive grease used to protect electrical connectors from moisture and corrosion.
  
• Short Circuit: An unwanted connection allowing excessive current to flow, risking damage.
  
• Conduit: Protective tubing used to shield wiring from mechanical damage.
  

Real-World Example
An operator faced a recurrent starter fuse blowing problem related to cab movement on an ASV VT70. Electrical troubleshooting revealed rubbing wires at a corner of the cab frame. After professional re-routing and applying protective wraps, the fuse blowing ceased, restoring reliable machine starting and operation.
Conclusion
Persistent fuse blowing in ASV machines often stems from wiring harness damage due to mechanical abrasion or poor routing near moving parts such as the cab lift. Early detection, careful inspection, and harness protection are critical to preventing electrical faults and maintaining machine uptime. Employing correct fuse ratings and proper repair techniques ensures safety and system reliability for ASV equipment operators.