New Holland UCM 5291 – UCM (Universal Control Module): Aux Control Function: Solenoid Reverse (B) Supply Open Circuit

The control module has detected a break in the electrical circuit (an open circuit) that supplies voltage or ground to the "Reverse" (B) directional solenoid on the auxiliary hydraulic control valve. This prevents the machine from operating the auxiliary hydraulics in the reverse direction.

• L213
• L215
• L216
• L218
• L220
• L221
• L223
• L225
• L228
• L230
• L234
• C227
• C232
• C234
• C237
• C238
• C245
• SR175
• SV185
• SV250
• TR270

1. 1

   Inspect the wiring harness leading from the UCM to the auxiliary hydraulic control valve block for severed wires, chafing, or rodent damage.

2. 2

   Disconnect the harness at the Reverse (B) solenoid and inspect the pins for corrosion, moisture, or pushed-out terminals.

3. 3

   Measure the resistance across the pins of the Reverse (B) solenoid coil using a multimeter to check for an open coil (infinite resistance).

4. 4

   Check the continuity of the supply and ground wires from the solenoid connector back to the UCM harness to isolate the break if the coil tests good.

5. 5

   Inspect the UCM fuses and the Electric Auxiliary Hydraulic fuses in the main fuse panel.

1. 1

   Park the machine on a level surface, lower the boom completely, turn off the engine, and disconnect the negative battery cable.

   Ensure the machine is safe to work on.

2. 2

   Relieve hydraulic system pressure according to the operator's manual.

   Depressurize the system before working on hydraulic components.

3. 3

   Locate the auxiliary hydraulic control valve block.

   Usually accessed by raising the cab or opening the rear/top access panels, depending on the model.

4. 4

   Disconnect the electrical connector from the Reverse (B) solenoid.

   Prepare the solenoid for removal or wiring repair.

5. 5

   If your diagnostics proved the solenoid coil is open/failed: Remove the retaining nut at the end of the solenoid stem and slide the faulty coil off the valve cartridge.

   Remove the defective coil.

6. 6

   Slide the new OEM replacement coil onto the stem and torque the retaining nut to spec.

   Install the new coil.

7. 7

   If the coil was good but the wiring was broken: Splice and repair the broken wire in the harness using weather-sealed heat-shrink connectors, or replace the damaged connector pigtail.

   Repair the open circuit in the wiring harness.

8. 8

   Reconnect the solenoid harness, reconnect the battery, and turn the key on.

   Restore power to the machine.

9. 9

   Clear the UCM fault codes and test the auxiliary hydraulic circuit in both forward and reverse.

   Ensure the code does not return and the attachment functions properly.