New Holland ENG 3125 – Engine Controller (EDC - Electronic Diesel Control / Engine ECU): Hand Throttle - Channel 2 Below Range Min.

The Engine Control Unit (ECU) has detected that the voltage signal from the second channel of the hand throttle position sensor has dropped below the minimum acceptable threshold (typically below 0.25V - 0.5V on a 5V reference circuit). This condition is usually caused by a failed potentiometer track, an open circuit (broken wire), or a short to ground in the sensor wiring.

• T8 Series (T8.275, T8.300, T8.330, T8.360, T8.390, T8.420)
• T8000 Series (T8010–T8050)
• TG Series (TG215–TG305)
• T9/T9000 Series
• TJ Series
• TM Series
• T6000 Series
• TS Series
• TL Series
• CR9090 Combine
• CX8080 Combine
• CX8090 Tier 4A Combine
• W170B Wheel Loader
• W190B Tier 3 Wheel Loader

1. 1

   Visual Inspection: Inspect the wiring harness and the 3-pin electrical connector at the hand throttle potentiometer in the cab console. Look for corrosion, pushed-out pins, or wire chafing.

2. 2

   Voltage Supply Check: Turn the key ON (engine off). Verify that the Engine ECU is supplying a steady 5V reference voltage and a good ground to the potentiometer connector.

3. 3

   Signal Sweep Test: Using a multimeter, back-probe the Channel 2 signal wire. Slowly move the hand throttle lever from the idle position to full throttle. The voltage should change smoothly and linearly. If the voltage drops out entirely, spikes, or stays below the minimum range, the potentiometer is internally faulty.

4. 4

   Mechanical Inspection: Check the physical hand throttle lever and linkage for excessive play or broken components that might cause the sensor to over-travel past its intended physical limit.

1. 1

   Disconnect Power

   Power down the machine, remove the key, and disconnect the battery to prevent electrical shorts.

2. 2

   Access the Sensor

   Remove the interior trim panels on the right-hand console or armrest to access the base of the hand throttle lever assembly.

3. 3

   Disconnect Wiring

   Unplug the electrical wiring harness connector from the hand throttle potentiometer.

4. 4

   Remove the Sensor

   Remove the retaining screws or clips securing the potentiometer to the throttle lever mechanism and slide the faulty sensor off the shaft.

5. 5

   Install the New Sensor

   Install the new potentiometer, ensuring the internal tang or linkage aligns correctly with the throttle lever shaft so it sweeps the correct range.

6. 6

   Reassembly

   Secure the potentiometer with the retaining screws and reconnect the electrical harness connector. Reassemble the console/armrest trim panels.

7. 7

   Calibration

   Reconnect the battery. Turn the key on and use the tractor's onboard display calibration menu (or a CNH diagnostic tool) to calibrate the new hand throttle sensor limits (teaching the ECU the new minimum and maximum voltage values).

8. 8

   Clear Codes

   Clear the ENG 3125 fault code and test the engine RPM response to verify the repair.