New Holland 18040 – Armrest control module (ACM) / Armrest Control Unit (ARU): EHR 1 Lever Position Low Voltage

The system has detected a voltage from the number 1 Electronic Hydraulic Remote (EHR) lever position sensor that is below the expected operational range. This suggests a potential short circuit to ground, an open circuit, or a failure within the sensor itself. The electronic control module relies on a specific voltage range from this sensor to determine the operator's intended position for the hydraulic remote valve. When the voltage is too low, the controller cannot accurately read the lever's position, triggering the fault.

• T4.80F
• T4.90F
• T4.100F
• T4.110F
• T4.80LP
• T4.90LP
• T4.100LP
• T4.110LP
• T4.80N
• T4.80V
• T4.90N
• T4.90V
• T4.100N
• T4.100V
• T4.110N
• T4.110V
• T6.140
• T6.145
• T6.150
• T6.155
• T6.160
• T6.165
• T6.175
• T6030
• T6050
• T6070
• T6080
• T6090
• T7.170
• T7.175
• T7.185
• T7.190
• T7.200
• T7.210
• T7.220
• T7.225
• T7.230
• T7.235
• T7.245
• T7.250
• T7.260
• T7.270
• T7.290
• T7.315
• T7030
• T7040
• T7050
• T7060
• T7070
• T8.275
• T8.300
• T8.320
• T8.330
• T8.350
• T8.360
• T8.390
• T8.410
• T8.420
• T8.435
• T9.435
• T9.450
• T9.480
• T9.505
• T9.530
• T9.560
• T9.565
• T9.600
• T9.615
• T9.645
• T9.670
• T9.700
• TG245
• TG255

1. 1

   Carefully inspect the wiring harness leading to the armrest controller and the EHR levers for any signs of damage, chafing, or loose connections. Wires can break internally within the insulation, especially where the harness flexes with seat movement. Gently pulling on each wire may reveal a 'stretchy' feel, indicating an internal break.

2. 2

   Review the tractor's fault code history for any other active codes, particularly those related to the armrest controller being offline or communication issues, as these could indicate a broader electrical problem.

3. 3

   Perform a Lever Wiggle Test: When the fault is active (often indicated by a cylinder icon on the A-post display), try wiggling each EHR lever one at a time. If wiggling the EHR 1 lever causes the fault light to turn off, it strongly suggests a failing potentiometer within that lever.

4. 4

   Perform a Potentiometer Resistance Test: If you have access to the armrest's internal components, disconnect the wiring from the EHR 1 lever and use an ohmmeter to measure the resistance between the center pin and one of the outer pins of the potentiometer's connector. Slowly move the lever through its full range of motion; the resistance should change smoothly. Any sudden jumps, drops to zero, or infinite resistance readings indicate a faulty potentiometer.

5. 5

   Perform Voltage Checks: For more advanced diagnostics, back-probe the connector with the key on to check for the correct 5-volt reference supply and the signal voltage from the potentiometer. The signal wire's voltage should change smoothly as the lever is moved.

1. 1

   Component Replacement

   Based on diagnostic findings, the most common repair is the replacement of the faulty EHR lever assembly, which contains the potentiometer. In some cases, just the potentiometer may be replaceable.

2. 2

   Access the Armrest

   Disassemble the armrest console to gain access to the EHR lever assemblies. This will likely involve removing covers and panels.

3. 3

   Replace the Lever/Potentiometer

   Disconnect the wiring harness from the faulty EHR 1 lever and unbolt it from the armrest frame. Install the new lever, ensuring it is securely mounted and the wiring is reconnected.

4. 4

   EHR Lever Calibration

   After replacing the lever, a calibration procedure must be performed to allow the control module to learn the new lever's neutral, full raise, full lower, and float position voltages. Access the tractor's diagnostic 'H' menu through the instrument cluster, navigate to the EHR or remote valve calibration section, and follow the on-screen prompts to move the specific lever to its various positions (neutral, raise, lower, float) to store the new values. Once complete, turn the key off to save the settings.