New Holland TMF 21 – Armrest Controller (ARU): Hitch Load Command potentiometer is failed in the Armrest Controller

The controller is receiving an out-of-range, open, or shorted voltage signal from the rotary dial/potentiometer used by the operator to set the hitch draft load command.

• New Holland T9 Series
• New Holland T8 Series
• New Holland TJ Series
• New Holland TJ275
• New Holland TJ425
• New Holland TJ430
• New Holland TJ450
• New Holland TJ530
• New Holland TG Series
• New Holland T70 Series

1. 1

   Check the main connector to the armrest controller (often C137) to ensure it is correctly installed, clean, and fully seated.

2. 2

   Inspect the data bus wires, power wires, and ground wires leading to the armrest controller for chafing or breaks.

3. 3

   Access the diagnostic menu on the instrumentation display to view the live voltage of the Hitch Load Command potentiometer. A reading pegged at 0V or 5V indicates a short or open circuit.

4. 4

   Attempt the Armrest Controller Calibration mode. If the potentiometer is in a valid range, an asterisk (*) will appear to select 'Draft'. If failed, it will force 'No Draft' (position-only hitch).

1. 1

   Disconnect Power

   Turn off the key and disconnect the battery to prevent shorting sensitive CAN-bus components.

2. 2

   Access the Armrest Console

   Remove the retaining screws holding the right-hand armrest console cover in place.

3. 3

   Inspect the Potentiometer

   Locate the Hitch Load Command potentiometer inside the armrest. Inspect its local sub-harness and solder joints/connector pins for damage.

4. 4

   Replace the Component

   If the wiring is intact but the potentiometer fails the resistance/voltage test, remove the retaining nut and knob, unplug the potentiometer, and install the replacement. (Note: In some severe cases of board failure, the entire Armrest Processor Module must be replaced).

5. 5

   Reassemble

   Reinstall the armrest cover and reconnect the battery.

6. 6

   Recalibrate

   Turn the key on and perform the Hitch Calibration procedure via the display (using the PROG key) to teach the controller the new potentiometer's minimum and maximum voltage values.