New Holland UCM 4783 – UCM: Two speed: Solenoid Supply Short to Power

The control module has sensed a higher-than-normal voltage on the Two Speed Solenoid circuit. The fault becomes active when the machine's Two Speed function is turned OFF, but the Two Speed Solenoid output voltage (measured at connector X-CN3A, pin 25) remains greater than 8 Volts. This causes the machine to automatically enable the 'Ground Drive Limp Home' operating mode.

• L213
• L215
• L218
• L220
• L223
• L225
• L230
• C227
• C232
• C238

1. 1

   Connect the Electronic Service Tool (EST) to the service port, start and operate the machine to verify if the fault code is actively recorded

2. 2

   Inspect the UCM connections and the Two Speed solenoid connections to ensure they are secure, tight, and free of corrosion, abrasion, or damage

3. 3

   Trace the wiring harness from the UCM to the Two Speed solenoid, looking for pinched wires, rubbed-through insulation (causing a short to power), or incorrect attachment

4. 4

   Measure the resistance through the harness and the solenoid wire to chassis ground to check for electrical shorts

1. 1

   Clear and Retest

   If the fault code does not return after clearing it and operating the machine, the issue was intermittent. Return the machine to service. If code 4783 returns, proceed to the next step.

2. 2

   Harness/Connector Repair

   If the visual inspection reveals damage to the wiring harness or connectors, repair or replace the affected harness sections or connectors.

3. 3

   Test/Replace the Solenoid

   If the wiring and connectors are in good condition, the Two Speed Solenoid itself may have failed internally. Temporarily install a known-good replacement solenoid and retest the machine. If the fault clears, permanently install the new solenoid.

4. 4

   Test/Replace the UCM

   If replacing the solenoid does not resolve the high-voltage reading, the UCM has suffered an internal failure. Temporarily replace the UCM, program it if necessary, and retest to confirm the elimination of the fault.