New Holland UCM 5601 – UCM: Aux Control Function: Loader Auxiliary Solenoid(s) Short to Power

The system has detected that the electrical circuit controlling the loader's auxiliary hydraulic solenoid(s) is shorted to a power source (12V). This means voltage is present on the control circuit when it shouldn't be, which can cause the auxiliary hydraulics to function erratically, become stuck on, or be disabled by the controller to prevent damage.

• L218
• L220
• L223
• L225
• L230
• C227
• C232
• C238
• SR175
• SV250

1. 1

   Visual Inspection: Inspect the wiring harness running from the UCM to the auxiliary hydraulic control valve block (usually located under the cab or near the loader arm pivots). Look for pinched wires, chafed insulation, or melted loom where the control wire might be touching a 12V supply wire.

2. 2

   Disconnect Test: Disconnect the electrical connector at the loader auxiliary solenoid(s). Turn the key ON. If the fault code changes from 5601 (Short to Power) to 5603 (Solenoids Return Open Circuit), the wiring harness is likely fine, and the solenoid coil itself is internally shorted.

3. 3

   Harness Pin-Out: With the battery disconnected and the UCM and solenoid unplugged, use a multimeter to check for continuity between the solenoid control wire and any 12V power supply wires in the harness. There should be no continuity (infinite resistance).

4. 4

   Connector Check: Inspect the UCM connectors and the solenoid connectors for water intrusion, corrosion, or bent pins that could bridge the power and control circuits.

1. 1

   Prepare the Machine

   Lower the loader arms to the ground (or secure them on mechanical locks if they must be raised). Turn off the engine, remove the key, and disconnect the negative battery cable.

2. 2

   Locate the Solenoids

   Lift and secure the cab (if necessary on your specific model) to access the main hydraulic control valve block. Locate the auxiliary directional solenoids.

3. 3

   Repair Wiring (If Applicable)

   If the diagnostic checks revealed a short in the harness, carefully open the wire loom at the damaged section. Splice and solder the damaged wires, seal with heat-shrink tubing, and re-loom the harness. Route it away from pinch points.

4. 4

   Replace the Solenoid (If Applicable)

   Unplug the electrical connector from the faulty auxiliary solenoid. Remove the retaining nut holding the solenoid coil to the valve stem. Slide the old solenoid coil off the valve cartridge. Slide the new solenoid coil onto the cartridge and tighten the retaining nut (do not over-tighten, or you may distort the cartridge). Reconnect the electrical harness.

5. 5

   Reassembly and Testing

   Lower the cab, reconnect the battery, and turn the key ON. Clear the stored UCM fault codes using the instrument cluster or a diagnostic tool. Start the machine and test the auxiliary hydraulic functions to ensure the code does not return.