Massey Ferguson 91.03 – ECU: Engine Throttle Sensor Voltage Issue

Triggers when the signal voltage from the Throttle Position Sensor (TPS) or foot pedal is outside the normal operating range (typically below 0.5V or above 4.5V). The ECU relies on this variable voltage signal to determine pedal pressure and translate it into precise fuel injection and RPM output. If the voltage is erratic, missing, or falls outside the acceptable threshold, the ECU logs this fault and may force the tractor into a limited operating mode.

• 7614
• 7615
• 7616
• 7618
• 7619
• 7620
• 7622
• 7624
• 7626
• Interim Tier 4 (2012-2015)
• 4707
• 4708
• 4709
• 4710
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 7714
• 7715
• 7716
• 7718
• 7719
• 7720
• 7722
• 7724
• 7726

1. 1

   Check the foot throttle pedal assembly for physical damage, debris obstruction, or mechanical sticking.

2. 2

   Inspect the wiring harness and connectors between the foot throttle sensor and the ECU for micro-cracks in circuit traces, corrosion, or loose pins.

3. 3

   Disconnect the sensor from the ECU and check the reference terminal on the connector (with the key on) for a steady 5 VDC supplied by the ECU.

4. 4

   Reconnect the sensor, back-probe the signal wire, and slowly depress the throttle pedal to ensure the voltage fluctuates smoothly (between 0.5V and 4.5V) without dead spots or erratic jumps.

1. 1

   Verify the Code

   Connect a diagnostic tool (such as the AGCO Electronic Diagnostic Tool) to confirm 00091.03 is the active code.

2. 2

   Test the Sensor

   Perform the multimeter sweep test. If the voltage reading is erratic, drops out, or stays stuck at an out-of-range value while sweeping the pedal, the sensor has failed internally.

3. 3

   Replace the Sensor

   If the sensor fails the sweep test, remove the mounting hardware securing the foot throttle sensor/TPS to the pedal assembly and install the replacement part.

4. 4

   Check the ECU

   If the sensor tests perfectly and the wiring harness has continuity, the issue may be module-level damage within the ECU itself (e.g., faulty resistors, damaged MOSFETs, or degraded solder joints distorting the voltage interpretation). In this case, the ECU will need to be sent to a specialist for repair or replaced.

5. 5

   Clear and Calibrate

   Once the repair is made, use the diagnostic tool to clear the fault codes. Some models may require a brief calibration procedure for the new throttle pedal resolution potentiometer. Test the throttle response to ensure full RPM range is restored.