When the Pedal Goes Silent: Diagnosing Accelerator Failure in the New Holland 115B

[MikePhua]

The Problem Unfolds
It began like any other workday—until the New Holland 115B backhoe loader suddenly stopped responding to the accelerator pedal. The machine still moved when the manual accelerator switch was used, but the foot pedal had gone dead. After cooling down, the pedal worked again briefly before failing once more. This intermittent behavior pointed to a deeper issue, possibly electrical or mechanical.
Electronic Pedal Assembly: A Likely Culprit
The 115B uses an electronic accelerator pedal, which can fail due to wear, moisture intrusion, or internal sensor faults. One technician noted that the pedal assembly (part number 317370-25-003) costs around $400, and emphasized the importance of verifying compatibility across different production years. A faulty pedal sensor can send incorrect signals—or none at all—to the engine control unit, causing the throttle to become unresponsive.
Crankcase Ventilation and Filter Blockage
Further inspection revealed a clogged crankcase gas filter beneath the engine cover. This blockage prevented proper ventilation, leading to pressure buildup and erratic engine behavior. Once the filter was cleaned, the machine resumed normal operation. This highlights a common oversight: neglecting internal filters that aren’t part of routine maintenance checks.
Power Shift Transmission Quirks
The operator also reported that the power shift transmission wasn’t smooth, especially when climbing hills. This could be linked to solenoid timing issues or hydraulic pressure inconsistencies. According to the New Holland B115B service manual, the transmission relies on precise coordination between torque converter stall tests, valve pressures, and gear engagement timing. A misbehaving transmission can amplify throttle issues, especially under load.
A Broader Look: Common Electrical Faults in New Holland Machines
Electrical problems in New Holland tractors are notoriously tricky. Experts recommend checking:

• Alternator output (should read 13.5–14.5 volts while running)
  
• Grounding points and wiring harnesses
  
• Sensor connectors, especially near the pedal and throttle body
  

These checks can reveal hidden corrosion or loose connections that mimic more serious failures.
A Field Story: Lessons from the Unexpected
In rural New Jersey, a utility crew faced a similar issue with a New Holland loader. The pedal failed mid-operation, forcing them to rely on the manual throttle. After hours of troubleshooting, they discovered a mouse nest inside the pedal housing—chewed wires and all. The fix was simple, but the downtime cost them a full day’s work. It’s a reminder that sometimes the smallest culprits cause the biggest headaches.
Industry Insight: Smart Diagnostics on the Rise
In 2024, New Holland began rolling out smart diagnostic systems in newer models, allowing real-time monitoring of pedal response, transmission behavior, and filter status. These systems aim to reduce guesswork and improve uptime. While the 115B predates these features, retrofit kits are being explored for legacy machines.
Conclusion: A Multi-Faceted Fix
The New Holland 115B’s accelerator issue wasn’t just a pedal problem—it was a convergence of electronic, mechanical, and maintenance factors. From clogged filters to aging sensors, each component played a role. The lesson? When a machine stops listening to your foot, it’s time to listen to the machine.