Case IH NH4182 – ARU: EHR Control No.4 Short Circuit

The Armrest Control Unit (ARU) or related hydraulic controller has detected a short circuit in the electrical circuit for the number 4 Electronic Hydraulic Remote (EHR) valve. This indicates an electrical failure that prevents the remote valve pilot head (valve driver) from properly controlling the hydraulic flow for that specific remote circuit.

• Magnum 235
• Magnum 260
• Magnum 290
• Magnum 315
• Magnum 340
• Steiger
• Quadtrac
• Puma
• MXM

1. 1

   Visually inspect the wiring harness leading to the #4 remote valve pilot head for pinched, frayed, or melted wires. On articulated tractors like the Steiger and Quadtrac, pay close attention to the large harness that runs through the articulation point, as chafing and wire damage are common there.

2. 2

   Disconnect the electrical connector at the #4 pilot head and inspect terminals for corrosion, moisture intrusion, or bent/dislocated pins. Clean and secure the connection if any issues are found.

3. 3

   Perform a component swap test: swap the suspected faulty #4 pilot head with a known working one (e.g., #3). Clear codes and operate the tractor to see if the fault follows the pilot head or stays with the #4 circuit.

4. 4

   If the fault remains with the #4 remote circuit after the swap test (indicating a wiring issue), use a multimeter to test the wiring harness for continuity to power (short to 12V) on the signal wire.

1. 1

   Prepare machine for service

   Park the tractor on a level surface, lower all implements to the ground, turn off the engine, engage the park brake, and chock the wheels.

2. 2

   Isolate the Fault

   Perform the diagnostic checks listed above to confirm whether the pilot head or the wiring is the cause.

3. 3

   Replace EHR pilot head (if faulty)

   If the swap test confirmed the pilot head is faulty, unbolt and remove it from the hydraulic valve stack. Install the new pilot head, ensuring seals/O-rings are correctly seated, and securely connect the electrical connector. It is best practice to ensure all pilot heads have the most current software installed; this may require a dealer visit for a software update.

4. 4

   Repair wiring harness (if faulty)

   If the swap test and multimeter testing confirmed a wiring issue, trace the harness from the #4 remote valve back to the controller. Repair damaged sections using appropriate solder and heat-shrink methods, or replace the damaged section. Ensure the harness is routed away from pinch points or abrasion sources.

5. 5

   Calibrate and verify system

   Start the tractor and clear all fault codes using the display or diagnostic tool. Perform a calibration of the remote valves through the tractor's diagnostic menu, then operate the #4 remote valve to verify the repair was successful.