Massey Ferguson 91.04 – Engine Control Unit (ECU): Engine Throttle Sensor Voltage Issue

The engine control module has detected that the analog signal voltage from the primary accelerator pedal potentiometer (throttle sensor) has dropped below the minimum acceptable threshold (typically below 0.1V or 0.3V). This indicates a short to ground or an open circuit in the sensor itself or its wiring harness. When this fault is active, the system typically defaults to a "limp home" mode, restricting the engine to a fixed low idle (e.g., 1200 RPM) and ignoring physical pedal inputs for safety.

• 4710
• 7724S
• 5712SL
• Interim Tier 4 (2012-2015)
• 7722
• 7722S
• 7615
• 5613
• 5713SL
• 7720S
• 7716
• 7718
• T4
• 7715
• 5710SL
• 7726
• 7616
• 7618
• 5608
• 4708
• 7619
• 7626
• 7726S
• 7624
• 4707
• 4709
• 5711SL
• 7614
• 7718S
• 5610
• 7620
• 7719
• 7714
• 7716S
• T4 (2015-2021)
• 5612
• 7622
• 7720
• Tier 4 (2015-2021)
• 5611
• 7715S
• 5609
• 7724
• 5400
• 6700
• 7700
• 8700

1. 1

   Check the physical condition of the accelerator pedal assembly, ensuring no debris is blocking movement and the return spring is intact.

2. 2

   Inspect the wiring harness and connector at the throttle position sensor for moisture, corrosion, backed-out pins, or chafed wires shorting against the chassis.

3. 3

   Verify the sensor is receiving the correct 5V reference voltage and has a solid ground from the ECU using a multimeter.

4. 4

   Perform a signal sweep test by back-probing the signal wire with the key ON (engine off) and slowly depressing the pedal. Voltage should smoothly increase; if stuck below 0.1V - 0.3V, the sensor is internally shorted or the signal wire is broken/shorted to ground.

1. 1

   Power Down

   Turn off the tractor, remove the key, and disconnect the negative battery cable to prevent electrical spikes.

2. 2

   Access the Sensor

   Locate the throttle position sensor/potentiometer, which is mounted directly to the base or pivot point of the accelerator pedal inside the cab.

3. 3

   Disconnect

   Unplug the electrical harness connector from the sensor.

4. 4

   Remove the Sensor

   Remove the mounting screws or bolts securing the potentiometer to the pedal linkage.

5. 5

   Install the New Part

   Mount the replacement OEM throttle sensor to the pedal assembly, ensuring the mechanical linkage aligns correctly with the sensor's rotary tang. Secure the fasteners.

6. 6

   Reconnect

   Plug the electrical harness back into the sensor and reconnect the battery.

7. 7

   Calibration / Code Clearing

   Turn the ignition to the ON position. Using a diagnostic tool (such as Massey Ferguson WinTest or AGCO EDT), clear the inactive 000091.04 fault code. Depending on the specific tractor series, a pedal calibration routine may need to be run via the diagnostic tool or dash menu so the ECU can learn the new minimum and maximum voltage limits of the replacement sensor.

8. 8

   Test

   Start the engine and verify that the throttle responds smoothly and the fault code does not return.