New Holland NH 4181 – Central Control Module (CCM) / Central Controller (XCM) / Display Unit (DU) Module: EHR Control No.4 open circuit

The tractor's control system has detected an open electrical circuit, a loss of signal, or a disconnected component in the circuit for the 4th Electronic Hydraulic Remote (EHR) control lever/valve.

• T6 Series (e.g., T6010, T6020, T6030, T6040, T6050, T6060, T6070)
• T7 Series (e.g., T7.220, T7.235, T7.250, T7.260, T7.270)
• T8 Series
• T9 Series
• T5000 Series (e.g., T5040 - T5070)
• TM Series (e.g., TM120, TM175)

1. 1

   Visual Inspection: Check the EHR valve connector, the extension harness connector, and the central controller (XCM/CCM) connector. Ensure the connectors are fully seated, not damaged, and that the pins are tight and free of corrosion.

2. 2

   Potentiometer Resistance Test: Disconnect the EHR control unit connector. While operating the No. 4 lever from extend to float, measure the resistance on the component side. Depending on the specific pins, resistance should typically sweep smoothly between 100 Ohms and 900 Ohms. If the resistance is out of specification or shows an open loop, the lever potentiometer is faulty.

3. 3

   Voltage Supply Check: Turn the key ON. Measure the voltage at the harness side of the control unit connector. You should see a +5 Volt reference signal. If the voltage is missing or significantly lower, there is a harness issue.

4. 4

   Harness Continuity Test: Turn the key OFF. Disconnect the connectors at both the EHR control unit and the central controller. Measure resistance between the corresponding pins on both ends of the harness to check for an open circuit. Wiggle the harness and connectors during the test to check for intermittent breaks.

5. 5

   CAN BUS Check (if applicable to the valve module): Measure the resistance across the CAN BUS pins. It should read approximately 60 Ohms. If it reads 120 Ohms or shows an open circuit, there is a break in the CAN BUS wiring to the terminating resistor or controller.

1. 1

   Turn the ignition key to the OFF position and ensure the tractor is safely parked.

2. 2

   Disconnect the wiring harness connectors at the No. 4 EHR control lever and the central controller.

3. 3

   Based on your diagnostic findings, if the harness failed the continuity test, trace the wiring harness for the No. 4 remote.

   Look for pinched, rubbed, or broken wires (especially near cab pivot points or tight bends).

4. 4

   Repair the broken wire using proper splicing techniques, or replace the affected harness section.

5. 5

   If the harness and 5V supply are intact but the lever failed the resistance test, remove the faulty EHR control unit/lever assembly from the armrest or side console and install a replacement.

6. 6

   Reconnect all electrical connectors securely.

7. 7

   Turn the key ON, clear the error code from the diagnostic menu, and test the No. 4 remote lever to verify normal operation.

   Note: Some modules may require a brief calibration procedure after replacing an EHR component.