New Holland UCM 5122 – UCM: Boom Raise/Lower: Pin B Short to Power / Short to Ground / Open Circuit

The control module senses that the signal from the Right Joystick's Forward-Backward (F-B) axis has failed. The fault becomes active when the voltage on the module's connector (X-CN1B pin 13) drops below 0.2 V or exceeds 4.8 V.

• L213
• L215
• L218
• L220
• L223
• L225
• L230
• L316
• SR175
• C227
• C232
• C238

1. 1

   Back-probe or measure the voltage on the UCM connector X-CN1B pin 13 to verify if it is outside the normal 0.5 V to 4.5 V range

2. 2

   Inspect the wiring harness from the Right Joystick to the UCM for pinched wires, rubbed insulation, or disconnected/corroded pins on Pin B

3. 3

   Ensure the UCM is receiving proper power and ground, as voltage irregularities can cause false sensor readings

1. 1

   Disconnect Power

   Turn off the machine and utilize the battery quick-disconnect switch (if equipped) or disconnect the negative battery cable to prevent electrical shorts during service.

2. 2

   Access the Components

   Gain access to the UCM (typically located under the cab or behind the interior panels) and the base of the right-hand joystick.

3. 3

   Harness Repair

   If the diagnostic checks revealed a broken wire, short, or severe corrosion in the EH chassis/cab wiring harness, repair the damaged section of the wire or replace the harness entirely.

4. 4

   Joystick Replacement

   If the wiring tests perfectly fine but the voltage output from the joystick remains below 0.2 V or above 4.8 V, the internal potentiometer/sensor on the joystick's F-B axis has failed. You must replace the Right Electro-Hydraulic Joystick assembly.

5. 5

   Reassembly & Testing

   Reconnect the battery. Turn the key on and verify that the UCM 5122 code is no longer active.

6. 6

   Clear Codes

   Use a diagnostic tool or DTC eraser to permanently clear the historical error code from the UCM memory. Test the boom raise/lower function to ensure full operational range.