Fault Phenomenon: Volvo L120 wheel loader pressing the accelerator pedal, engine speed does not change or jumps.

Troubleshooting Process:
– Checked sensor: dual potentiometer signals inside pedal inconsistent.
– Checked wiring: pedal harness worn or connector loose.
– Checked mechanical: pedal return spring broken or stuck.
– Checked controller: ECU receiving incorrect signal.

Root Cause: The internal potentiometer of the electronic accelerator pedal is worn, causing intermittent or incorrect output signals, triggering ECU protection mode.

Required Parts: Replace electronic accelerator pedal assembly.