New Holland 18059 – ACU: Joystick 2 Proportional Rocker Switch Voltage Low

The Armrest Control Unit (ACU) has detected that the voltage from the Joystick 2 proportional rocker switch is below the expected operational range. This low voltage condition prevents the controller from accurately reading operator input, which can impair the functionality of the associated hydraulic remote valve. The fault is typically caused by a short circuit to ground, an open circuit in the wiring harness, or an internal failure of the switch itself.

• T7.175
• T7.220
• T7.235
• T.250
• T7.260
• T7.270
• T8.300
• T8.360
• T8.390

1. 1

   Visually inspect the wiring harness running to and from the armrest joystick for pinching, chafing, or damaged insulation.

2. 2

   Disconnect the electrical connectors for the joystick and the Armrest Control Unit to inspect pins and sockets for corrosion, moisture intrusion, or damage.

3. 3

   Perform a wiggle test on the wiring harness between the joystick and control unit with the ignition on to check for intermittent connections or broken wires.

4. 4

   Use a multimeter at the switch connector to verify the presence of reference voltage (typically 5V or 12V) and ground.

5. 5

   Measure the signal wire voltage while actuating the rocker switch; a reading of zero or near-zero volts confirms the low voltage fault.

1. 1

   Confirm the Fault

   Verify that the fault code 18059 is active or stored in the Armrest Control Unit using the tractor's diagnostic display or a service tool.

2. 2

   Perform Diagnostic Checks

   Carry out the visual and connector inspections as detailed above.

3. 3

   Isolate the Fault

   If the wiring and connectors appear to be in good condition, determine if the fault lies with the switch or the controller by substituting a known-good joystick assembly if available.

4. 4

   Wiring Repair

   If a wiring issue is identified, repair the damaged section of the harness by soldering and heat-shrinking the repaired wires to ensure a durable and weather-resistant connection.

5. 5

   Component Replacement

   If diagnostics point to a faulty joystick rocker switch, replace the switch or the entire joystick assembly. If the switch and wiring are confirmed to be good, replace the Armrest Control Unit (less common).

6. 6

   Clear Fault Codes

   After completing the repairs, clear all fault codes from the Armrest Control Unit.

7. 7

   Test Operation

   Operate the Joystick 2 proportional rocker switch and verify that the associated hydraulic function works correctly and that the fault code does not reappear.