Case IH 51085 – AUX (Auxiliary Valve Controller) / TMF (Tractor Multi-Function): Aux 4th Lower solenoid failed open or short circuit.

The controller has detected an electrical fault in the circuit for the 4th auxiliary (remote) hydraulic valve's 'lower' (or retract) solenoid. The system is seeing either infinite resistance (an open circuit, such as a broken wire, disconnected plug, or burnt-out internal coil) or a lack of resistance (a short circuit to ground).

• MX Magnum
• Case IH MX Series (MX100, MX120, MX135, MX210, MX230)
• Case IH TG Series
• Case IH Puma Series
• Case IH Steiger / STX 4WD Series (STX425, STX500)

1. 1

   Visually inspect the rear remote valve stack, specifically the 4th valve wiring harness and connector, for chafed wires, corrosion inside the connector pins, or a loose plug.

2. 2

   Perform a coil resistance test by disconnecting the harness from the 4th lower solenoid and measuring resistance across the two pins (OL indicates an open circuit; 0 ohms indicates a short to ground).

3. 3

   Perform a swap test by exchanging the 4th lower solenoid coil with the 3rd lower solenoid coil. If the code changes to 51075, the solenoid is faulty. If it remains 51085, the issue is in the wiring harness or AUX controller.

4. 4

   Check for voltage at the harness connector with the key ON while commanding the 4th remote to lower from the cab to ensure the AUX controller is sending the signal.

1. 1

   Depressurize the System

   Turn off the tractor engine. Turn the key back to the ON position (engine off) and move the 4th remote lever/switch back and forth to relieve any trapped hydraulic pressure in the circuit. Turn the key OFF.

2. 2

   Locate the Component

   Go to the rear hydraulic remote stack and locate the 4th valve block. Identify the specific solenoid responsible for the lower/retract function.

3. 3

   Disconnect

   Unplug the electrical harness connector from the faulty solenoid.

4. 4

   Remove the Coil

   Remove the retaining nut or bolt at the end of the solenoid stem. Slide the faulty electromagnetic coil off the proportional valve cartridge. (Note: If you are only replacing the coil, no hydraulic fluid will leak. If you must replace the entire proportional valve cartridge, unscrew it from the block and be prepared with a catch pan for a small amount of hydraulic fluid).

5. 5

   Install the New Part

   Slide the new solenoid coil onto the valve stem. Reinstall and tighten the retaining nut to OEM torque specs (do not overtighten, as this can distort the cartridge).

6. 6

   Reconnect

   Plug the electrical harness back into the new solenoid.

7. 7

   Test

   Start the tractor, clear the inactive fault codes from the dash/monitor, and operate the 4th remote valve to ensure proper function and that code 51085 does not return.