New Holland NH 4040 – Arm Rest Module (ARU): Supply Voltage too low

The supply voltage reaching the Arm Rest Module (ARU) has dropped below the minimum operating threshold of 8 Volts.

• T7.175
• T7.190
• T7.210
• T7.225 AutoCommand
• TVT 135
• TVT 145
• TVT 155
• TVT 170
• TVT 195
• TJ500
• T4020
• T4030
• T4040
• T4050

1. 1

   Verify that the tractor's base battery voltage is healthy (12V+) and the alternator is charging properly

2. 2

   Check the specific fuses supplying power to the ARU (e.g., 5-Amp fuses F19 and F20 on TVT models)

3. 3

   Disconnect the harness at the Arm Rest Module and use a multimeter to measure the supply voltage pins to verify if the voltage is dropping below 8V

4. 4

   Inspect the wiring harness leading to the armrest for chafing, pinch points (common in moving armrests/seats), corrosion, or loose ground connections

1. 1

   Resolve Power Supply Issues

   If the voltage at the ARU connector is below 8V, trace the circuit back to the fuse panel. Repair any damaged wiring, clean corroded pins, or replace blown 5A fuses.

2. 2

   Replace the ARU

   If the harness delivers proper voltage (>12V) under load but the ARU still logs code 4040, the module has an internal hardware fault and must be replaced.

3. 3

   Clear Stored Codes

   After the repair, the fault codes must be cleared from the EEPROM. On newer models like the T7 series, this is done via the Central Control Unit (CCU) diagnostic menu (e.g., navigating to the H8 menu to clear stored EEPROM error codes).

4. 4

   Recalibrate

   If a new ARU is installed, you may need to recalibrate armrest functions (like the lower valve or draft control) depending on the tractor's specific configuration.