Diagnosing Drive Motor Failure on the Genie GS-3268 RT Scissor Lift

[MikePhua]

The GS-3268 RT and Its Role in Rough Terrain Access
The Genie GS-3268 RT is a rough terrain scissor lift designed for outdoor construction and maintenance work. Manufactured by Genie Industries, a subsidiary of Terex Corporation, the GS-3268 RT was introduced to meet the growing demand for compact, four-wheel-drive aerial platforms that could operate on uneven surfaces. With a working height of approximately 38 feet and a lift capacity of 1,000 lbs, the GS-3268 RT became a popular choice for contractors needing reliable access in rugged environments.
Its 4x4 drive system, powered by hydraulic motors at each wheel, allows it to climb grades and traverse gravel, mud, and jobsite debris. The lift is available in gas, diesel, and dual-fuel configurations, with a robust hydraulic system that powers both the lift and drive functions.
Symptoms of Partial Drive Failure
A common issue reported on the GS-3268 RT involves two of the four wheels failing to drive, while the other two remain functional. In most cases, the working wheels are positioned diagonally (kitty-corner) from each other, suggesting a hydraulic circuit imbalance or solenoid malfunction.
Operators may observe:

• Loss of traction on one side of the machine
  
• Reduced climbing ability or spinning wheels
  
• Uneven response when steering or driving
  
• Low pressure readings at one of the hydraulic test ports
  

This behavior typically points to a failure in one of the drive motor circuits, either due to a faulty solenoid valve, blocked hydraulic line, or internal motor damage.
Drive Solenoids and Circuit Isolation
The GS-3268 RT uses solenoid valves to control hydraulic flow to each drive motor. These solenoids are mounted near the hydraulic manifold and are responsible for directing fluid to the appropriate motor based on joystick input. Each motor has two solenoids—one for forward and one for reverse.
To isolate the fault:

• Identify which wheels are not driving
  
• Swap solenoids between working and non-working motors
  
• Observe whether the problem follows the solenoid or remains with the motor
  
• Check voltage at the solenoid terminals during operation
  
• Inspect wiring harnesses for damage or corrosion
  

If swapping solenoids causes the issue to move to a different wheel, the solenoid is likely at fault. If the problem remains with the same wheel, the motor or hydraulic line may be compromised.
Hydraulic Pressure Testing and Interpretation
The GS-3268 RT includes two hydraulic test ports for monitoring drive circuit pressure. Normal operating pressure should be consistent across both ports when the machine is in motion. If one port shows significantly lower pressure, it may indicate:

• A blocked or kinked hydraulic line
  
• A failed motor seal or internal bypass
  
• A malfunctioning flow control valve
  
• Air intrusion or cavitation in the circuit
  

Pressure testing should be performed with the machine on level ground, under load, and with all wheels engaged. Use a calibrated gauge and record readings during forward and reverse operation.
Motor Disassembly and Inspection
If solenoids and wiring are ruled out, the drive motors themselves may require inspection. Disassembly involves:

• Removing the wheel and hub assembly
  
• Disconnecting hydraulic lines and electrical connectors
  
• Opening the motor housing to inspect gears, seals, and bearings
  
• Checking for scoring, contamination, or wear
  

In one documented case, a technician found that two motors had internal scoring due to water intrusion. The motors had been submerged during a flood cleanup job and were never properly flushed. Replacing the seals and flushing the system restored full function.
Recommendations for Repair and Prevention
To maintain drive performance on the GS-3268 RT:

• Perform monthly solenoid function tests
  
• Flush hydraulic fluid annually or after exposure to contaminants
  
• Use OEM-grade filters and fluid to prevent cavitation
  
• Inspect wheel motors for leaks and unusual noise
  
• Keep a spare solenoid and pressure gauge in the service kit
  
• Label solenoids and connectors to simplify troubleshooting
  

For machines operating in wet or corrosive environments, consider installing protective boots over solenoids and connectors. This reduces the risk of electrical shorts and connector degradation.
Conclusion
The Genie GS-3268 RT is a capable rough terrain lift, but its drive system depends on precise hydraulic and electrical coordination. When two wheels stop driving, the issue often lies in solenoid control or hydraulic imbalance. With methodical testing, component swapping, and pressure diagnostics, technicians can restore full mobility and keep the lift working where it belongs—above the ground, not stuck in the mud.