JLG 600SJ Platform Control Issues: Diagnosis and Solutions

[MikePhua]

The JLG 600SJ is one of the most widely used telescopic boom lifts, known for its ability to extend to high altitudes, offering a versatile platform for work at significant heights. This equipment is essential in industries such as construction, maintenance, and utilities, where access to high, hard-to-reach places is required. Like many other complex machines, the JLG 600SJ can experience occasional issues, and one such issue that operators may encounter is malfunctioning platform controls. These issues can hinder the efficient operation of the lift, making it critical to understand the causes and solutions to ensure the safe and effective use of the equipment.
Overview of the JLG 600SJ
The JLG 600SJ is part of the JLG Industries lineup of aerial work platforms, specifically designed for high-reaching tasks in construction and industrial environments. With a maximum working height of 60 feet (18 meters) and a horizontal outreach of 39 feet (12 meters), the JLG 600SJ provides a versatile platform for both indoor and outdoor applications. The machine is equipped with a telescoping boom that allows operators to access difficult-to-reach areas with ease.
JLG Industries, founded in 1969, is a leading manufacturer of access equipment, with a reputation for producing reliable and durable lifts. The 600SJ is part of JLG's series of "SkyPower" lifts, which are known for their advanced hydraulic systems and robust build. Despite its reliability, like any piece of heavy machinery, the JLG 600SJ can face operational issues that require troubleshooting and maintenance.
Understanding the Platform Control System
The platform control system in the JLG 600SJ is a critical component of the lift, as it allows the operator to control the elevation, boom extension, and rotation of the machine from the platform itself. This system includes a set of buttons, joysticks, and levers, all connected to the machine’s hydraulic and electrical systems. The platform control allows for precise manipulation of the lift's movements, making it essential for efficient work at height.
The system is powered by electrical components, including a control panel, sensors, and wiring that communicate with the lift's onboard hydraulic pumps and valves. If any component of this system fails, the lift may become difficult or impossible to operate from the platform, which poses a safety risk to the operator.
Common Platform Control Issues

1. Unresponsive or Malfunctioning Controls
   Symptoms: The platform controls fail to respond to the operator’s commands. When pressing buttons or manipulating the joystick, the boom or lift does not move as expected.
   Possible Causes:
   • Electrical failure: A blown fuse or malfunctioning relay could prevent power from reaching the control system.
     
   • Loose or corroded connections: If the wiring between the platform control system and the machine’s electrical system is compromised, it could cause communication issues.
     
   • Faulty platform control panel: The control panel itself may have experienced wear or damage, resulting in intermittent or complete loss of functionality.
     
   Solution:
   • Start by inspecting the fuse and relay connections to ensure they are not damaged or blown.
     
   • Check all wiring and connections between the platform control system and the lift’s electrical components. Repair or replace any damaged or corroded parts.
     
   • If the issue persists, the platform control panel may need to be replaced or repaired by a qualified technician.
     
2. Platform Control Switches Not Responding
   Symptoms: Specific switches on the platform control panel do not respond when activated, but the rest of the controls appear to be working.
   Possible Causes:
   • Faulty switches: Over time, switches can wear out due to constant use and exposure to harsh environmental conditions.
     
   • Contaminated switch contacts: Dirt, grime, or moisture may cause the switch contacts to malfunction or become sticky, preventing proper operation.
     
   Solution:
   • Clean the control switches and ensure that they are free from dirt and debris. Applying a cleaning agent specifically designed for electrical components can help.
     
   • If cleaning does not solve the problem, consider replacing the switches. Be sure to use compatible parts as specified by the manufacturer to maintain system integrity.
     
3. Intermittent Operation of the Platform Controls
   Symptoms: The platform controls work intermittently, causing the boom to move erratically or stop responding unexpectedly.
   Possible Causes:
   • Loose or damaged wiring: If wiring connections are loose, intermittent connections can cause the control system to fail intermittently.
     
   • Hydraulic system malfunction: A problem in the hydraulic system, such as a failing pump or hydraulic valve, can affect the movement of the boom and platform.
     
   Solution:
   • Check all electrical connections for signs of wear, looseness, or corrosion. Tighten or replace any faulty connections.
     
   • Inspect the hydraulic system, including hoses, pumps, and valves, for leaks or wear. Ensure the hydraulic fluid is at the correct level and replace any worn components.
     
4. Error Codes or Warning Lights on the Control Panel
   Symptoms: The control panel displays error codes or warning lights that prevent the machine from operating normally.
   Possible Causes:
   • Diagnostic error: The system’s onboard diagnostics may detect an issue within the electrical or hydraulic system.
     
   • Sensor failure: Sensors that monitor the position of the boom or the hydraulic pressure could be malfunctioning and sending incorrect readings to the control panel.
     
   Solution:
   • Refer to the machine’s user manual for the meaning of any displayed error codes and follow the troubleshooting steps outlined in the manual.
     
   • If the error is related to a sensor or diagnostic system, the faulty component may need to be replaced by a certified technician.
     

Preventative Maintenance for Platform Control Issues
To minimize the risk of platform control issues on the JLG 600SJ, regular preventative maintenance is essential. Here are some best practices to keep the platform control system in optimal condition:

• Regularly check electrical connections: Ensure that all connections are clean, tight, and free of corrosion. Use dielectric grease on electrical terminals to protect against moisture and dirt.
  
• Inspect control switches: Periodically test the platform control switches to ensure they are responsive. Clean and lubricate the switches to prevent buildup that could hinder their operation.
  
• Monitor hydraulic system health: Keep an eye on hydraulic fluid levels and check for leaks. Regularly inspect hydraulic hoses and connections for signs of wear.
  
• Perform diagnostic checks: Use the built-in diagnostic system to perform routine checks on the lift’s performance. Address any detected issues promptly to prevent more significant problems from developing.
  

Conclusion
The JLG 600SJ is a versatile and reliable aerial work platform, but like any complex piece of machinery, it is not immune to technical issues. The platform control system is central to the lift's operation, and any malfunction in this system can pose significant safety risks to the operator. Common issues, such as unresponsive controls or intermittent operation, can typically be traced back to electrical failures, faulty switches, or hydraulic problems. Regular inspection, cleaning, and maintenance can prevent many of these issues from occurring, ensuring that the JLG 600SJ remains a valuable tool for high-reach tasks.
By understanding the potential causes and solutions for platform control issues, operators can ensure that their JLG 600SJ remains in peak operating condition, maximizing safety and efficiency on the job site.