08-24-2025, 12:14 AM
Introduction
The JLG 400S is a diesel-powered telescopic boom lift designed for various applications, including construction, maintenance, and industrial tasks. Known for its versatility and performance, the 400S offers a platform height of 40 feet and a horizontal outreach of 33 feet 3 inches, making it suitable for tasks requiring extended reach and maneuverability.
Specifications
- Platform Height: 40 ft (12.19 m)
- Working Height: 46 ft (14.02 m)
- Horizontal Outreach: 33 ft 3 in (10.13 m)
- Platform Capacity: 600 lb (272 kg) unrestricted; 1,000 lb (453.6 kg) restricted
- Engine: Diesel-powered, typically a 3-cylinder Deutz engine
- Drive: 4WD hydrostatic drive with oscillating axle
- Tires: Foam-filled for durability
- Weight: Approximately 12,650 lbs (5,740 kg)
- Swing: 360 degrees continuous
- Platform Size: 96" x 36" (2.44 m x 0.91 m)
Operators have reported various issues with the JLG 400S, often related to electrical and hydraulic systems. Common problems include intermittent drive or steering, boom movement failures, and engine performance issues.
Electrical System Troubleshooting
- Battery and Connections: Inspect the main battery connections and fuses for corrosion or damage. Ensure the control box wiring harness is intact and free from loose or frayed wires. Test the emergency stop switch and joystick controls for proper function.
- Control Modules: Use a diagnostic tool to check for fault codes in the drive/steer control module. Ensure that hydraulic valves linked to steering are actuating properly. Regularly clean connectors and test joystick potentiometers for wear.
- Fluid Levels and Filters: Check hydraulic fluid levels and inspect filters for clogs. Low fluid levels or clogged filters can cause delays in hydraulic response.
- Hydraulic Valves: Ensure that hydraulic valves are functioning correctly and are not obstructed. Regular maintenance and timely replacement of hydraulic components can prevent system failures.
- Fuel System: Check for fuel contamination or air in the fuel lines. Ensure that the fuel filter is clean and properly installed.
- Ignition System: Inspect spark plugs and ignition coils for wear or damage. Replace faulty components to restore engine performance.
- Cooling System: Ensure that the radiator and cooling fans are clean and functioning properly. Overheating can lead to engine stalling or reduced performance.
- Regular Inspections: Conduct routine inspections of the electrical and hydraulic systems to identify potential issues before they become major problems.
- Component Replacement: Replace worn or damaged components promptly to maintain optimal performance and safety.
- Operator Training: Ensure that operators are trained in the proper use and maintenance of the JLG 400S to prevent misuse and prolong the lifespan of the equipment.
The JLG 400S is a reliable and versatile boom lift that, when properly maintained, can provide years of service. By addressing common issues promptly and adhering to recommended maintenance practices, operators can ensure the longevity and performance of the equipment. For detailed troubleshooting and maintenance procedures, refer to the manufacturer's service manual or consult with a certified technician.
