Case IH Hb – Hitch Controller or Electronic Draft Control (EDC) module: Short to 12 volts on the raise solenoid circuit

The controller has detected that the electrical circuit responsible for energizing the hitch raise solenoid is receiving 12 volts when it shouldn't be, or the solenoid coil itself has an internal short circuit.

• MX Maxxum
• 7200/8900 series Magnum
• MX Series (MX100, MX110, MX120, MX135, MX150, MX170)
• older Magnum Series

1. 1

   Coil Resistance Test (Solenoid internal short cause): Turn the tractor key OFF. Disconnect the electrical connector to the EDC valve raise solenoid at the rear hitch control valve block. Measure resistance across the two terminals. Expected: 6.4 to 8.0 Ohms. If significantly lower, the coil is internally shorted.

2. 2

   Harness Voltage Test (Wiring short to power cause): With the solenoid disconnected, turn the key switch ON (engine off). Measure voltage between the power pin on the harness connector and chassis ground. If 12 volts is present without commanding the hitch to raise, the wiring harness is shorted to a power source.

3. 3

   Harness Continuity Test: Check the wiring harness for continuity from the EDC controller pins to the solenoid connector to ensure there are no broken or rubbed-through wires touching adjacent power lines.

1. 1

   Ensure the tractor is turned off, the key is removed, and the implement is fully lowered to the ground to relieve hydraulic pressure.

   Perform this step if the solenoid coil is faulty.

2. 2

   Disconnect the wiring harness from the raise solenoid.

3. 3

   Remove the retaining nut at the end of the solenoid valve stem.

4. 4

   Slide the faulty electromagnetic coil off the valve cartridge.

   You usually do not need to remove the hydraulic cartridge itself, which prevents fluid loss.

5. 5

   Slide the new replacement coil onto the stem and tighten the retaining nut.

6. 6

   Reconnect the electrical harness.

7. 7

   Trace the wire from the raise solenoid back to the EDC controller.

   Perform this step if the wiring harness is shorted.

8. 8

   Inspect common rub points, such as where the harness passes through the cab floor or near the rear axle housing.

9. 9

   Repair the shorted section of the wire using heat-shrink butt connectors and re-loom the harness.

10. 10

    Clear the stored fault codes.

    On the EDC panel, enter the diagnostic 'H' menu, scroll to the HC (Clear all stored fault codes) prompt, and execute the clear command.