New Holland UCM 9159 – UCM (Universal Control Module): Pattern Select (ISO/H): Short to Ground

The control module has detected a short circuit to ground in the wiring or internal circuitry of the ISO/H Pattern Select switch.

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

1. 1

   Inspect the wiring harness running from the UCM to the Pattern Select rocker switch for pinched wires, chafed insulation, or bare wires touching the metal chassis.

2. 2

   Disconnect the Pattern Select switch and inspect the connector for moisture, corrosion, or melted/bent pins. Repeat this check at the UCM harness connector.

3. 3

   With the battery disconnected and the switch unplugged, use a multimeter to test the switch's signal wire for continuity to ground to verify if the harness is shorted.

4. 4

   Test the rocker switch itself for an internal short to ground using a multimeter.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the negative battery cable to prevent electrical damage.

2. 2

   Access the Switch

   Remove the necessary trim or paneling on the cab console to access the rear of the Pattern Select rocker switch.

3. 3

   Remove the Faulty Component

   Unplug the wiring harness connector from the switch. If the switch failed the diagnostic test, push the retaining tabs on the sides of the switch to pop it out of the panel.

4. 4

   Repair Wiring

   If the diagnostic tests pointed to a harness short, locate the chafed wire, splice in a new section of wire using weather-resistant heat-shrink connectors, and re-loom the harness.

5. 5

   Install New Switch

   Snap the new OEM rocker switch into the panel and plug the wiring harness back in.

6. 6

   Reassemble and Reconnect

   Secure the console panels and reconnect the negative battery cable.

7. 7

   Calibration/Testing

   Turn the machine on. Push and hold the ISO/H pattern select switch to your desired pattern for a few seconds. An audible alarm should sound to confirm the pattern switch was successful, and the switch should illuminate only on the selected side.

8. 8

   Clear Codes

   Activate the hydraulic system by pressing the OPERATE button and verify that fault code UCM 9159 has moved to an inactive state or is cleared from the display.