EPC 000091.04 – B79 Accelerator Pedal Potentiometer, Voltage Too Low

EPC 000091.04 (EPC 91.04)

Code: 000091.04

Shortcode: 91.04


This error code, EPC 000091.04, indicates that the control unit has detected a voltage below 0.3 volts at the signal input of the accelerator pedal potentiometer (B79). This low voltage condition suggests a short to ground in the circuit.


When this error is detected, the control system may misinterpret the accelerator pedal position, potentially leading to poor throttle response and reduced engine performance. This can result in sluggish or inconsistent acceleration.


Inspect Wiring for Shorts to Ground:

  • Check the wiring associated with the accelerator pedal potentiometer for any signs of short circuits to ground. Look for damaged insulation or exposed wires.

Test Potentiometer Functionality:

  • Use diagnostic tools to test the accelerator pedal potentiometer (B79). Ensure it is functioning correctly and providing accurate voltage readings.

Verify Connections:

  • Inspect all connectors and terminals in the circuit for secure and clean connections. Repair or replace any that are loose or corroded.

Check for Ground Faults:

  • Use a multimeter to test for any ground faults in the wiring leading to the potentiometer.

Reset and Test System:

  • After addressing any issues found, reset the system and test the accelerator pedal response to ensure the problem is resolved.


Maintaining the integrity of the wiring and potentiometer is essential for reliable throttle response. Regular checks can help identify and address potential issues before they affect performance.

Control Units: John Deere

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