New Holland UCM 5202 – UCM: Boom Raise/Lower: Pin B Short to Power / Short to Ground / Open Circuit

The control module is detecting an abnormal electrical condition on Pin B of the circuit responsible for the boom's vertical movement. The system is seeing voltage or resistance values that are outside the expected operating range. This typically indicates a broken wire (open circuit), a wire rubbing against the chassis (short to ground), a wire touching a live voltage source (short to power), a failed axis sensor inside the joystick, or a burnt-out control valve solenoid.

• L213
• L215
• L218
• L220
• L223
• L225
• L230
• L313
• L316
• L318
• L320
• SR175
• SR200
• C227
• C232
• C238
• C327
• C330
• C332

1. 1

   Secure the Machine: Lower the boom completely to the ground. If the boom must be raised for access, ensure it is securely resting on the mechanical boom lock pins. Turn off the ignition.

2. 2

   Visual Wiring Inspection: Inspect the wiring harness running from the UCM to the joystick and down to the hydraulic control valve. Look for chafed wires, pinched harnesses, or disconnected plugs.

3. 3

   Connector Check: Disconnect the harness at the joystick and the boom raise/lower solenoid. Inspect Pin B specifically for corrosion, moisture intrusion, or pushed-back/bent pins.

4. 4

   Component Testing (Solenoid): Use a multimeter to test the resistance of the boom raise/lower control valve solenoid. An infinite reading indicates an open circuit (burnt coil), while a reading of zero indicates an internal short.

5. 5

   Component Testing (Joystick): Check the voltage sweep of the joystick output to the UCM. If the voltage drops out or spikes erratically when moving the joystick on the boom axis, the internal sensor has failed.

1. 1

   Safely park the machine, secure the boom, and turn off the ignition.

2. 2

   Disconnect the negative battery cable to prevent electrical spikes during the repair.

3. 3

   If repairing wiring: Cut out the damaged section of the harness and splice in new wiring using weather-sealed heat-shrink connectors, or replace the damaged connector pigtail.

4. 4

   If replacing the solenoid: Clean the area around the hydraulic control valve to prevent contamination. Relieve any residual hydraulic pressure. Disconnect the electrical plug, unthread the faulty lockout/control solenoid from the valve block, and install the new solenoid.

5. 5

   If replacing the joystick: Remove the side console/armrest trim panels. Disconnect the main harness plug from the bottom of the joystick. Unbolt the joystick base from the armrest and install the replacement unit.

6. 6

   Reconnect the negative battery cable.

7. 7

   Turn the key to the ON position. Use the instrument cluster display to view and clear the inactive fault codes (often done by pressing the ENTER button twice to silence and clear).

8. 8

   Start the machine and test the boom raise and lower functions to verify the repair.