New Holland UCM 4781 – UCM (Utility Control Module / Universal Control Module): Two speed: Solenoid Supply Open Circuit

The UCM has sent a command signal to energize the Two Speed solenoid, but no voltage or current draw is detected on the circuit. This indicates an "open circuit" condition, meaning there is a break in the wiring, a disconnected plug, a burned-out solenoid coil, or an internal module failure. When this code is active, the machine's Two Speed operating mode is disabled by the controller as a safety precaution.

• 200 Series Skid Steer Loaders
• 200 Series Compact Track Loaders
• L213
• L215
• L218
• L220
• L223
• L225
• L230
• C227
• C232
• C238
• Case construction models

1. 1

   Connect the Electronic Service Tool to the diagnostic port and verify that code 4781 is currently active

2. 2

   Check the wiring harness and the X-2SPD connector (Two Speed Valve Solenoid to Chassis) for physical damage, corrosion, or backed-out pins

3. 3

   Perform a jumper test: Disconnect the Two Speed solenoid, install a jumper wire between pin A and pin B on the X-2SPD harness connector, reconnect the UCM connectors (X-CN3A), and turn the ignition switch ON

4. 4

   Activate the two-speed feature while monitoring the fault code screen to evaluate the jumper test

5. 5

   If fault code 4781 goes inactive and fault code 4782 (Short to Ground) becomes active, the UCM and wiring harness are functioning properly, indicating the Two Speed Solenoid has failed

6. 6

   If fault code 4781 remains active and 4782 does not appear, the solenoid is likely fine, but there is a broken wire in the harness or the UCM has suffered an internal failure

1. 1

   Wiring Repair

   If the jumper test fails, trace the wiring from the X-2SPD connector back to the UCM (specifically checking X-CN3A pin 25). Repair any broken wires or replace the affected harness section.

2. 2

   Solenoid Replacement

   If the jumper test passes (Result A), the solenoid coil is open. Remove the retaining nut on the two-speed valve block, slide the old solenoid coil off the cartridge, and install the replacement solenoid.

3. 3

   UCM Replacement

   If the wiring tests perfectly continuous with no shorts or opens, but the UCM still fails to detect the circuit during the jumper test, the UCM has an internal failure. Temporarily plug in a test UCM to confirm the fault clears before permanently installing and programming a new module.

4. 4

   Clear Codes

   After repairs, cycle the key, activate the two-speed function to ensure proper operation, and clear the inactive codes using the service tool.