New Holland UCM 5145 – UCM: Aux Control Function: Pin B Short to Power

The control module is detecting an abnormally high voltage on the "Pin B" signal circuit of the auxiliary hydraulic thumbwheel sensor (located on the joystick). A short to power means the sensor's signal wire is making direct contact with a voltage supply line (such as a 5V reference or 12V battery power), or the sensor inside the joystick has failed internally and is bleeding reference voltage directly to the signal pin.

• L213
• L215
• L218
• L220
• L223
• L225
• L230
• L313
• L316
• L318
• L320
• L321
• L328
• L334
• C227
• C232
• C238
• C327
• C332
• C338

1. 1

   Visually inspect the wiring harness running from the base of the joystick down into the side console for pinched wires, chafed insulation, or rubbing against the cab frame.

2. 2

   Perform a disconnect test: Turn the machine off, disconnect the main electrical connector for the affected joystick, and turn the key back ON. If the code changes to 5144 (open circuit), the short is internal to the joystick. If it remains 5145, the short is in the main wiring harness.

3. 3

   Inspect the pins at the joystick connector and the UCM for moisture, corrosion, or bent pins that could be bridging the power and signal circuits.

1. 1

   Prepare machine

   Turn off the machine, lower the boom completely (or engage the boom lock), and disconnect the negative battery cable.

2. 2

   Remove joystick hardware

   Remove the protective boot and the mounting hardware securing the affected joystick to the armrest/console.

3. 3

   Disconnect joystick

   Carefully pull the joystick assembly up to access the wiring harness and disconnect the main plug.

4. 4

   Install new joystick

   Install the new replacement joystick assembly and securely route the wiring harness to ensure it will not be pinched when the armrest is moved.

5. 5

   Reassemble console

   Reinstall the mounting hardware and the protective rubber boot.

6. 6

   Restore power

   Reconnect the battery and turn the key to the ON position.

7. 7

   Clear fault codes

   Verify that the UCM 5145 code has changed to an inactive state and clear the code using the instrument cluster or an Electronic Service Tool (EST).

8. 8

   Calibrate EH controls

   Depending on the machine's software version, perform a quick EH control calibration procedure via the advanced display panel or EST to learn the new thumbwheel center/span values.