JLG 1932E2 Scissor Lift Reverse Failure: Diagnosis, Repair, and Prevention

[MikePhua]

The JLG 1932E2 scissor lift has earned a reputation for reliability, efficiency, and durability in indoor maintenance and warehouse operations. However, as with any electrically controlled equipment, users may sometimes encounter motion-related failures that interrupt workflow and delay critical tasks. One such issue—when the lift will move forward but refuses to reverse—may seem minor, but its causes are often surprisingly complex. This article unpacks this issue in full: what causes it, how to diagnose it, and how to keep it from happening again.
Understanding the Drive System in the JLG 1932E2
The JLG 1932E2 operates using an electric direct drive system powered by DC motors and controlled through a series of relays, limit switches, joystick signals, and controller logic.
Key components involved in the drive system include:

• Joystick controller – The input device the operator uses to command motion.
  
• Directional relays (forward/reverse) – Electromagnetic switches that route electrical current to the drive motors depending on the chosen direction.
  
• Limit switches – Safety components that stop travel when certain boundaries are reached (e.g., pothole protection engaged or lift too high).
  
• Motor contactors – Larger relays capable of handling the current needed to drive the motors.
  
• Control card / logic board – Interprets input signals and enforces safety interlocks.
  
• Proximity sensors – Detect conditions like steering angle or platform position.
  

Symptoms of a Reverse Failure
Operators experiencing a reverse-only failure (i.e., the lift moves forward but not in reverse) often report:

• The lift powers on and functions normally except when trying to reverse.
  
• No fault codes or beeping errors.
  
• Forward motion is smooth and strong.
  
• Battery charge is sufficient, and hydraulics are responsive.
  
• Steering, raising, and lowering all function correctly.
  

In some cases, users may hear a faint “click” when trying to reverse, suggesting a relay is attempting to engage but failing.
Likely Causes of a Reverse Failure
Here is a breakdown of the most common culprits behind a JLG 1932E2 not going in reverse:

• Faulty reverse relay
  • One of the most common failures. A relay may click but fail to pass sufficient current due to worn contacts or internal damage.
    
• Joystick potentiometer malfunction
  • The joystick’s internal potentiometer sends varying voltage to determine direction. If the “reverse” range of movement fails, the lift won’t engage reverse.
    
• Broken or disconnected wire in the control harness
  • Wires leading from the joystick to the relay board can become damaged over time, especially in machines with years of vibration and movement.
    
• Direction signal not reaching the logic controller
  • Even if the relay is fine, if the logic controller never sees a valid reverse command, it won’t energize the reverse circuit.
    
• Limit switch engaged
  • A limit switch—especially one linked to platform height or pothole protection—can prevent reverse if it falsely indicates a hazard.
    
• Contactor failure
  • The contactor responsible for engaging reverse motion may have burnt contacts or mechanical failure.
    
• Motor brush wear (less common)
  • If the DC drive motor brushes are heavily worn or damaged, they may not respond equally in both directions.
    

Step-by-Step Troubleshooting Approach
To isolate and resolve the reverse failure issue, technicians and operators can follow this methodical diagnostic approach:

1. Test Forward and Reverse Relays
   • Swap the forward and reverse relays to see if the problem moves with the relay.
     
   • If reverse begins to work and forward stops, the relay is the issue.
     
2. Check Voltage at the Relays During Operation
   • Use a multimeter to verify that voltage is sent to the reverse relay when the joystick is pulled back.
     
   • If no voltage is present, trace the signal back toward the joystick.
     
3. Inspect the Joystick Potentiometer
   • Use an ohmmeter or multimeter to verify the output voltage when moving the joystick forward and backward.
     
   • Ensure the full range of motion gives smooth voltage variation.
     
4. Inspect Wiring and Connections
   • Look for pinched, frayed, or corroded wires, especially near articulation points or the control box.
     
   • Pay close attention to connectors at the base of the joystick and the interface card.
     
5. Check Limit and Safety Switches
   • Ensure no limit switches are stuck or misaligned.
     
   • The pothole protection system, for example, can disable motion if falsely engaged.
     
6. Test Motor and Contactor
   • Manually test the drive motor in both directions by bypassing the relay (only if safe and experienced).
     
   • Inspect contactors for overheating signs or melted contacts.
     
7. Consult Diagnostic LED or Error Flash Codes
   • On some models, the control board has LED indicators that blink error codes.
     
   • Reference the JLG service manual for interpretation.
     

Real-World Story: The Warehouse Incident
In a distribution center outside Chicago, a maintenance worker was stranded on the raised platform of a JLG 1932E2. The machine worked fine during the ascent but refused to back away from a steel beam after repositioning. Panic set in briefly, but a mechanic on-site recognized the symptoms. Swapping the forward/reverse relays immediately solved the issue—one relay had burned slightly due to poor ventilation and high duty cycles.
This real-life example reminds us of the importance of basic electrical knowledge and being prepared with spare relays—especially when using older lifts for frequent shifts.
Additional Considerations for Legacy Machines
The 1932E2 is not a recent model. Machines from this generation may have:

• Worn or oxidized circuit boards
  
• Loose grounding connections
  
• Joystick drift due to mechanical fatigue
  

In these cases, refurbishment or parts replacement may be more cost-effective than extended troubleshooting.
Terminology Clarification

• Relay: An electrically operated switch that opens or closes circuits by receiving small control signals.
  
• Contactor: A relay designed to handle high current, typically used to control motors.
  
• Potentiometer: A variable resistor often used in joysticks to translate position into electrical signals.
  
• Limit Switch: A safety switch that prevents certain motions beyond safe ranges.
  

Preventive Maintenance Tips
To reduce the risk of control system failures in the future, implement a proactive maintenance schedule:

• Test all motion functions weekly, including reverse
  
• Keep all connectors dry and clean, using dielectric grease as needed
  
• Periodically remove and re-seat relays to prevent oxidation
  
• Avoid overloading the platform beyond rated capacity
  
• Ensure platform gate is fully latched before attempting motion
  

When to Call for Help
If after swapping relays and testing signal voltage the machine still won’t reverse, it’s time to involve a professional technician—especially if logic controller faults are suspected. JLG service centers can perform deeper diagnostics using factory tools and may offer reprogramming or updated control cards.
Final Thoughts
A JLG 1932E2 that won’t reverse can halt an entire job. But with a grounded understanding of how its electrical systems interact, even non-certified operators can confidently identify the root of the issue. In most cases, the failure is minor—like a relay or joystick problem—and can be fixed with inexpensive parts and basic tools.
Understanding your machine not only saves time and money but ensures your crew stays safe and productive. After all, troubleshooting is just another word for “listening carefully to what the machine is trying to tell you.”