New Holland NH 4179 – DU (Drive Unit) Control Module: EHR Control No.3 short circuit

The control module has detected a short circuit—either to ground or to a voltage source—in the electrical circuit of the control lever/potentiometer that operates the 3rd rear hydraulic remote valve.

• New Holland T6 / T6000 Series (T6010, T6020, T6030, T6040, T6050, T6060, T6070)
• New Holland T7 Series (T7.175, T7.220, T7.235, T7.250, T7.260, T7.270)

1. 1

   Inspect the EHR Control Lever No. 3 on the armrest/side console for physical damage, liquid intrusion, or sticking.

2. 2

   Trace the wiring harness from the No. 3 control lever down to the DU control module. Look for pinched wires, chafed insulation, or areas where the harness might be rubbing against the seat suspension or console frame.

3. 3

   Disconnect the EHR Control Lever No. 3. Use a multimeter to test the lever's internal potentiometer for an internal short circuit.

4. 4

   Test the tractor-side wiring harness for continuity to ground or a short to the 5V reference/12V supply lines.

5. 5

   Inspect the pins at both the lever connector and the DU module for corrosion, moisture, or bent pins that could be bridging circuits.

1. 1

   Disconnect Power

   Turn off the tractor and disconnect the negative battery cable to prevent electrical spikes during repair.

2. 2

   Access the Controls

   Remove the retaining screws for the armrest control panel or the side console cover to expose the underside of the EHR control levers.

3. 3

   Isolate the Fault

   Disconnect the electrical connector specifically for EHR Control Lever No. 3.

4. 4

   Repair Wiring

   If your multimeter tests in the diagnostic phase revealed a short in the wiring harness, splice and repair the damaged wires using heat-shrink butt connectors, or replace the affected harness section.

5. 5

   Replace the Lever

   If the wiring tests fine, the short is internal to the lever's potentiometer. Unbolt the faulty EHR Control Lever No. 3 assembly and install the replacement unit.

6. 6

   Reassembly

   Reconnect the wiring harness to the lever, reinstall the armrest/console covers, and reconnect the battery.

7. 7

   Calibration

   Turn the ignition key on. Clear the inactive NH 4179 code and perform the EHR lever calibration procedure via the instrument cluster or a diagnostic tool to teach the module the new potentiometer's neutral, extend, and retract voltage values.