New Holland UCM 5701 – UCM (Universal Control Module): Pattern Select (ISO/H): Short to Ground / Open Circuit

An electrical fault—either a broken wire (open circuit) or a wire shorting to the machine's chassis (short to ground)—in the circuit that monitors the ISO/H control pattern select switch.

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

1. 1

   Locate the ISO/H Pattern Select switch on the instrument panel and check the physical condition of the momentary rocker/push button.

2. 2

   Disconnect the switch and inspect the connector pins for corrosion, moisture, or pushed-out pins. Do the same at the UCM connector.

3. 3

   Using a multimeter, test the wiring harness between the Pattern Select switch and the UCM for continuity to ensure there is no open circuit.

4. 4

   Check for continuity to ground on the signal wires to rule out a short to ground.

5. 5

   Ensure the AUX roller switch on the right-hand joystick is in the neutral position, as the UCM will ignore pattern switch inputs if the AUX roller is active.

1. 1

   Power Down

   Turn off the machine and disconnect the negative battery cable (or use the battery disconnect switch if equipped) to prevent electrical spikes.

2. 2

   Access the Switch

   Remove the necessary trim on the instrument panel to access the rear of the ISO/H Pattern Select switch.

3. 3

   Remove and Replace

   Disconnect the wiring harness from the faulty switch. Pop the old switch out of the panel and snap the new replacement switch into place.

4. 4

   Reconnect

   Plug the wiring harness into the new switch and reconnect the battery.

5. 5

   Calibration / Testing

   Turn the machine on. Ensure the right-hand AUX roller switch is in neutral. Press and hold the ISO/H pattern select switch to the desired pattern for a few seconds. Listen for an audible alarm, which confirms the UCM has accepted the pattern change. Verify on the text display that the control pattern has changed and that the switch illuminates only on the selected side (ISO on the left, H on the right). Press the OPERATE button to activate the hydraulic system and test the joystick functions.