Case IH 4174 – DU Module: Rear EHR control No.2 - open circuit (DU module only)

The system has detected an open electrical circuit in the Rear Electro-Hydraulic Remote (EHR) valve No. 2. This means electrical continuity has been lost between the controller and the valve's solenoid, which is typically caused by a disconnected plug, a broken wire in the harness, or a burned-out (open) solenoid coil on the valve itself.

• Maxxum
• Puma 125
• Puma 140
• Puma 150
• Puma 165
• Puma 175
• Puma 180
• Puma 195
• Puma 210
• Puma 225
• Maxxum 110
• Maxxum 115
• Maxxum 125
• Maxxum 130
• Maxxum 140
• Maxxum 145
• Maxxum 150
• Magnum 235-340
• Steiger 350-600

1. 1

   Visual Inspection: Locate the rear EHR valve stack at the back of the tractor and identify valve No. 2. Check the electrical connector plugging into the solenoid for pushed-out pins, heavy corrosion, or a loose connection.

2. 2

   Harness Continuity Test: Disconnect the harness from the No. 2 EHR valve and the DU module. Use a multimeter to check for continuity on the power and ground wires. Look for chafing or breaks in the wiring harness, particularly where it routes near the cab suspension or hydraulic lines.

3. 3

   Coil Resistance Test: Measure the resistance across the pins of the No. 2 EHR valve solenoid coil. If the multimeter reads 'OL' (infinite resistance), the internal coil has failed open.

4. 4

   Swap Test: If the wiring tests fine, temporarily swap the electrical connector from EHR No. 1 or No. 3 onto the No. 2 valve. If the fault code changes to match the swapped circuit (e.g., 4171 for No. 1 open circuit), the valve coil is confirmed dead.

1. 1

   Depressurize the System

   Turn off the tractor, lower all implements to the ground, and cycle the remote levers/switches to relieve any residual hydraulic pressure in the system.

2. 2

   Disconnect Power

   Disconnect the tractor's battery to prevent electrical shorts during repair.

3. 3

   Remove the Faulty Component

   If the wiring harness is broken, splice and repair the wire using weather-sealed heat-shrink connectors, or replace the damaged harness section. If the valve coil is dead, thoroughly clean the area around the EHR valve stack to prevent dirt from entering the hydraulic system. Unbolt the No. 2 EHR valve section or its solenoid from the hydraulic manifold stack.

4. 4

   Install the New Valve/Solenoid

   Fit the replacement EHR valve section, ensuring all O-rings are properly seated and lubricated with clean hydraulic oil. Torque the mounting bolts to OEM specifications.

5. 5

   Reassemble

   Reconnect the electrical harness to the new valve. Reconnect the battery.

6. 6

   Calibrate the Valve

   Start the tractor. You will likely now see fault code 4173 (Rear EHR control No.2 – not calibrated). You must enter the tractor's H-Menu / calibration screen via the instrument cluster or AFS Pro monitor to perform the EHR spool calibration procedure so the DU module can learn the new valve's electrical thresholds.