Kubota P2122 – Engine Control Module (ECM) / Engine ECU: FPP1 Voltage High (Foot Pedal Position 1 Voltage High)

The Engine Control Module (ECM) detects that the voltage signal from the primary track of the electronic accelerator pedal is out of its expected range (exceeds a maximum threshold for longer than 0.5 seconds). This typically indicates a short to voltage in the signal wire, an open 5V return (ground) circuit, or an internal failure of the pedal sensor itself.

• WG1605
• WG1903
• WG2503
• V2403-CR
• V3307-CR
• SVL75-2
• SVL97-2
• KX033-4
• KX057-4
• U35-4
• U55
• L3540
• L4240
• M6-111

1. 1

   Visual Inspection: Inspect the wiring harness and connector at the accelerator pedal position sensor for broken wires, rubbed-through insulation causing a short to power, or corroded/bent pins.

2. 2

   Voltage Supply & Ground Test: Disconnect the pedal sensor, turn the key ON (engine off), and use a multimeter to verify a steady 5V reference signal from the ECM and a solid ground (5V return). An open ground will cause the signal voltage to default high.

3. 3

   Signal Sweep Test: With the sensor plugged in, back-probe the FPP1 signal wire and slowly depress the accelerator pedal. The voltage should sweep smoothly (typically 0.8V to 4.4V). If stuck at 5V, the sensor is internally shorted or the signal wire is shorted to power.

4. 4

   Continuity Test: If the sensor tests fine, disconnect the ECM and the pedal sensor to test the signal wire for continuity and ensure it is not shorted to another voltage-carrying wire in the harness.

1. 1

   Turn the ignition switch to the OFF position and disconnect the negative battery cable to prevent electrical shorts.

2. 2

   Locate the Foot Pedal Position sensor assembly at the base of the accelerator pedal (or on the cruise control/hand throttle lever, depending on the machine).

3. 3

   Depress the release tab and disconnect the electrical harness plug from the sensor.

4. 4

   Remove the mounting hardware (typically Phillips screws or small hex bolts) securing the sensor to the pedal assembly.

   Note: Be careful not to lose any metal spacers or spring-loaded shafts behind the sensor.

5. 5

   Install the new accelerator pedal position sensor, ensuring the internal spring/shaft aligns correctly with the pedal linkage.

6. 6

   Reinstall and tighten the mounting hardware.

7. 7

   Reconnect the electrical harness plug until it clicks securely.

8. 8

   Reconnect the negative battery cable.

9. 9

   Turn the key ON and use a compatible OBD-II or Kubota diagnostic scan tool to clear the P2122 fault code.

10. 10

    Start the engine and test the throttle response to ensure the machine accelerates smoothly and the limp mode is deactivated.