New Holland UCM 5703 – UCM: Pattern Select (ISO/H): Short to Power

The Universal Control Module (UCM) is detecting unexpected voltage on the circuit for the ISO/H Pattern Select Switch. A "Short to Power" indicates that the signal wire is receiving voltage (typically 12V) when it shouldn't be, which is usually caused by an internal short within the switch itself or a wiring harness failure where the signal wire is chafing against a live power wire.

• L213
• L215
• L218
• L220
• L223
• L225
• L230
• C227
• C232
• C238
• L316
• L318
• L320
• SR130
• SV185
• TR270

1. 1

   Visually inspect the ISO/H Pattern Select Switch in the cab for physical damage or moisture intrusion.

2. 2

   Trace and inspect the wiring harness from the back of the switch down to the UCM for pinched wires, melted insulation, or chafing against the cab frame.

3. 3

   Perform a voltage test to isolate the short: Turn the key ON (engine off), disconnect the harness from the switch, and probe the signal wire pin. If 12V is present, the harness is shorted; if no voltage is present, the switch has an internal short.

1. 1

   Power Down

   Turn off the machine, lower the loader arms to the ground, and disconnect the negative battery cable.

2. 2

   Access the Switch

   Remove the retaining screws for the instrument console panel where the Pattern Select Switch is mounted to access the rear connections.

3. 3

   Repair the Circuit

   If the harness is shorted: Locate the chafed or melted section of the wiring harness. Cut out the damaged section, splice in new wire using weather-sealed heat-shrink butt connectors, and re-loom the harness to prevent future chafing. If the switch is shorted: Depress the retaining tabs on the back of the Pattern Select Switch and push it out of the console panel. Snap the new OEM switch into place.

4. 4

   Reassembly

   Reconnect the switch harness and reinstall the console panel.

5. 5

   Clear Codes & Test

   Reconnect the battery and turn the key ON. Clear the inactive fault codes using the instrument cluster display or the Electronic Service Tool (EST).

6. 6

   Calibration/Verification

   Press the "OPERATE" button. Push and hold the new ISO - H pattern select switch to the desired pattern for a few seconds. An audible alarm will sound, and the text display will confirm the change to verify the repair was successful.