New Holland NH 4174 – Central Control Unit (CCU) / XCM (Central Controller) / Rear EHR Module: EHR Control No.2 open circuit

The central controller has detected an open electrical circuit (meaning a broken wire, disconnected plug, or a burnt-out internal solenoid coil) on the #2 rear remote valve.

• T6 series
• T7 series
• T8 series
• T9 series
• TM series (TM115-TM165)
• T6000 series (T6010-T6070)
• T7000 series (T7030-T7060)
• SP280
• SP480

1. 1

   Visually inspect the number 2 EHR valve connector, extension harness connectors, and central controller connector for secure connection, damage, and corrosion.

2. 2

   Measure resistance across the CAN BUS lines (should read approximately 60 Ohms; 120 Ohms indicates an open circuit, under 5 Ohms indicates a short).

3. 3

   Disconnect the EHR valve and central controller connectors, then measure resistance between corresponding signal pins while wiggling the harness to check for an intermittent open circuit (greater than 5 Ohms indicates a faulty harness).

4. 4

   With the valve disconnected, check for continuity between the EHR valve connector pins and the chassis ground to rule out a short to ground.

1. 1

   Power Down

   Turn off the ignition key and disconnect the battery to prevent electrical spikes during repair.

2. 2

   Harness Repair

   If your diagnostic checks revealed an open circuit in the wiring, trace the harness back from the #2 remote valve. Repair the broken wire or replace the damaged connector pigtail.

3. 3

   Valve Replacement Diagnosis

   If the wiring and connectors test perfectly, the open circuit is internal to the #2 EHR valve's solenoid coil.

4. 4

   Remove the Valve

   Clean the area around the rear remote stack to prevent dirt from entering the hydraulic system. Relieve any residual hydraulic pressure. Remove the retaining tie-bolts holding the #2 EHR valve section in the stack and carefully slide the valve out.

5. 5

   Install the New Valve

   Install the replacement EHR valve, ensuring all O-rings are properly seated between the valve slices. Torque the tie-bolts to the manufacturer's specification.

6. 6

   Reassembly and Testing

   Reconnect the electrical plug and the battery. Turn the key on, clear the inactive fault codes using the tractor's diagnostic menu or a service tool, and operate the #2 remote to verify normal operation and check for hydraulic leaks.