New Holland NH 6023 – Transmission Control Module: FWD solenoid open circuit

The control module has detected a break or loss of continuity in the electrical circuit supplying the Front Wheel Drive (FWD) solenoid. Because the FWD system is spring-applied and hydraulically released, an open circuit causes the solenoid to lose power and the FWD to default to the 'engaged' position, preventing the operator from turning it off.

• T7 Series
• T7.220
• T7.235
• T7.250
• T6000 Series
• T6010
• T6020
• T6030
• TM Series
• TM115
• TM135
• TM150
• TM165
• TS Series
• 40 Series
• 6640
• 7740
• 7840
• 8340
• Genesis / 70 Series
• 8670
• 8770
• 8870
• 8970

1. 1

   Visually inspect the wiring harness leading to the FWD solenoid for pulled wires, melted insulation, or rodent damage

2. 2

   Perform a magnetism test: with the key switch ON and FWD switch OFF, place a small steel screwdriver against the FWD solenoid to check for magnetism (lack of magnetism indicates no power or a dead coil)

3. 3

   Unplug the solenoid and measure resistance across its pins with a multimeter (expected is approx. 9.4 ohms; an infinite/OL reading confirms an internal open circuit)

4. 4

   Swap the electrical connectors between the FWD solenoid and the adjacent Differential Lock solenoid to see if the fault code changes to NH 7017, isolating the issue to the solenoid itself

1. 1

   Park the tractor on a level surface, turn off the engine, and apply the parking brake.

2. 2

   Locate the FWD solenoid.

   Depending on the tractor model, it is typically located at the rear of the tractor near the 3-point hitch top link mounting bracket, or at the bottom of the transmission behind the FWD clutch bulge.

3. 3

   Disconnect the electrical plug from the FWD solenoid.

   Clean the contacts with electrical contact cleaner to rule out a simple dirty connection.

4. 4

   Repair the wiring harness if damaged.

   If the wiring harness is damaged (e.g., pulled out of the bullet connector by brush), cut away the damaged wire, strip the ends, and splice in a new connector using weather-resistant heat-shrink crimp connectors to ensure a factory-grade seal.

5. 5

   Remove the old solenoid coil.

   If the solenoid failed the diagnostic tests, remove the retaining nut at the end of the solenoid stem and slide the old electromagnetic coil off the valve cartridge.

6. 6

   Install the new solenoid coil.

   Slide the new OEM solenoid coil onto the valve stem and tighten the retaining nut.

7. 7

   Reconnect the electrical harness plug.

   Ensure it clicks securely into place.

8. 8

   Test the repair.

   Turn the key on, clear the fault codes from the dashboard monitor, and test the FWD switch to ensure the 4WD engages and disengages properly.