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Introduction: When Foot Controls Fail in the Field
The Mustang 940E skid loader, manufactured in the mid-1990s, is a compact and versatile machine often used for snow removal, landscaping, and light construction. But like many older models, it’s prone to electrical and safety interlock issues—especially in the foot control system. This article explores a real-world case of intermittent foot pedal failure, delves into the underlying causes, and offers practical solutions for operators and mechanics alike.
Symptoms of the Problem
The Mustang 940E uses a solenoid-actuated safety lock system to prevent accidental movement of the lift and tilt functions. This system is tied to several safety inputs:
Common Causes of Foot Control Failure
In urgent cases—such as needing to plow snow before repairs—operators may remove the pedal lock pushrods entirely. This disables the safety lock but should only be done with full awareness of the risks. Always restore safety features once permanent repairs are made.
Real-World Anecdote: Winter Pressure and Quick Fixes
One Illinois operator faced this issue just before winter. After rewiring the safety switches and inspecting the plugs, the machine worked flawlessly for a day—only to relapse later. The urgency of snow season pushed him to consider bypassing the locks temporarily. This scenario is common in rural areas where equipment downtime can mean missed income or impassable driveways.
Why Auxiliary Hydraulics Still Work
Unlike lift and tilt, auxiliary hydraulics are not locked by the safety system. This design choice reflects the lower risk of injury from auxiliary functions, which typically power attachments like augers or sweepers. Lift and tilt, on the other hand, can cause crushing injuries if activated unintentionally.
Preventive Maintenance Recommendations
The Mustang 940E skid loader remains a reliable machine when maintained properly. But as it ages, electrical quirks and safety lock issues become more common. With a methodical approach—checking wiring, solenoids, and switch integrity—operators can restore functionality and ensure safe operation. And in the spirit of field ingenuity, sometimes a temporary fix is the bridge to a permanent solution.
The Mustang 940E skid loader, manufactured in the mid-1990s, is a compact and versatile machine often used for snow removal, landscaping, and light construction. But like many older models, it’s prone to electrical and safety interlock issues—especially in the foot control system. This article explores a real-world case of intermittent foot pedal failure, delves into the underlying causes, and offers practical solutions for operators and mechanics alike.
Symptoms of the Problem
- Foot controls for boom and bucket intermittently stop working.
- Clicking sounds are heard in the cab when the controls disengage.
- Sometimes the system resets and works again temporarily.
- Auxiliary hydraulics remain functional, suggesting selective lockout.
The Mustang 940E uses a solenoid-actuated safety lock system to prevent accidental movement of the lift and tilt functions. This system is tied to several safety inputs:
- Seat Safety Switch: Ensures the operator is seated before controls are enabled.
- Seat Belt Safety Switch: Confirms the operator is secured.
- Solenoid Lock Mechanism: Electrically releases pedal locks when safety conditions are met.
- Key Switch Circuit: Powers the control system and may be modified in older machines.
Common Causes of Foot Control Failure
- Faulty or Bypassed Safety Switches
- Previous owners may bypass seat or belt switches by splicing wires.
- Improper wiring can cause intermittent or permanent lockout.
- Previous owners may bypass seat or belt switches by splicing wires.
- Loose or Corroded Electrical Connections
- Harness plugs near the valve assembly may loosen over time.
- Moisture and vibration can degrade contact quality.
- Harness plugs near the valve assembly may loosen over time.
- Weak or Failing Solenoids
- Solenoids may lose strength, especially in cold weather.
- A weak solenoid may fail to fully disengage the pedal lock.
- Solenoids may lose strength, especially in cold weather.
- Modified Key Switch Wiring
- Some machines have jury-rigged ignition systems.
- A wire running from the key switch to the fuel relay may interfere with control logic.
- Remove the seat and inspect the valve assembly and solenoid bank.
- Check all wiring for splices, corrosion, and loose connectors.
- Test solenoids with a multimeter for proper resistance and voltage.
- Replace any damaged plugs or relays in the engine compartment.
- Restore factory wiring for seat and belt switches if previously bypassed.
- Consider replacing the solenoids if they show signs of weakness or erratic behavior.
In urgent cases—such as needing to plow snow before repairs—operators may remove the pedal lock pushrods entirely. This disables the safety lock but should only be done with full awareness of the risks. Always restore safety features once permanent repairs are made.
Real-World Anecdote: Winter Pressure and Quick Fixes
One Illinois operator faced this issue just before winter. After rewiring the safety switches and inspecting the plugs, the machine worked flawlessly for a day—only to relapse later. The urgency of snow season pushed him to consider bypassing the locks temporarily. This scenario is common in rural areas where equipment downtime can mean missed income or impassable driveways.
Why Auxiliary Hydraulics Still Work
Unlike lift and tilt, auxiliary hydraulics are not locked by the safety system. This design choice reflects the lower risk of injury from auxiliary functions, which typically power attachments like augers or sweepers. Lift and tilt, on the other hand, can cause crushing injuries if activated unintentionally.
Preventive Maintenance Recommendations
- Inspect and clean electrical connectors quarterly.
- Avoid bypassing safety systems unless absolutely necessary.
- Replace solenoids every 5–7 years or sooner if symptoms appear.
- Keep wiring diagrams on hand for troubleshooting.
- Use dielectric grease on plugs to prevent corrosion.
The Mustang 940E skid loader remains a reliable machine when maintained properly. But as it ages, electrical quirks and safety lock issues become more common. With a methodical approach—checking wiring, solenoids, and switch integrity—operators can restore functionality and ensure safe operation. And in the spirit of field ingenuity, sometimes a temporary fix is the bridge to a permanent solution.
