New Holland UCM 1911 – UCM: Power Supply: Rail 12VH1 - Left and Right Pump Reverse Input Power OFF

This code indicates a power supply failure or disconnection on the specific internal or external power rail (12VH1) that provides voltage to the left and right hydraulic pump reverse inputs.

• L213
• L216
• L218
• L220
• L221
• L223
• L225
• L228
• L230
• L234
• L316
• L318
• L320
• L323
• L325
• C227
• C232
• C234
• C237
• C238
• C245
• C327
• C332
• C334
• C337
• C345

1. 1

   Verify that the machine's battery voltage is within specification and that the battery disconnect switch is functioning properly.

2. 2

   Check the main power distribution box for blown fuses or faulty relays that supply power to the UCM, specifically those protecting the EH control circuits.

3. 3

   Inspect the wiring harness running from the UCM to the left and right hydraulic drive pumps. Look for chafed wires, open circuits, or shorts to ground that could cause the UCM to cut power to the 12VH1 rail to protect itself.

4. 4

   Disconnect the UCM connectors and inspect the pins for corrosion, moisture intrusion, or pushed-out pins.

1. 1

   Disconnect Power

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

2. 2

   Repair Wiring

   If the diagnostic checks revealed a short or open circuit in the pump reverse input wiring, repair the damaged section of the harness or replace the affected connector.

3. 3

   Replace Fuses

   If a short caused a fuse to blow, replace it with a fuse of the exact OEM amperage rating.

4. 4

   Replace the UCM

   If the wiring harness tests perfectly (proper continuity, no shorts to ground/power) and the UCM is receiving proper supply voltage but still fails to output power on Rail 12VH1, the UCM has suffered an internal hardware failure. Remove the mounting hardware and harness connectors to extract the faulty UCM.

5. 5

   Install and Flash

   Install the new UCM. Note: A replacement UCM is blank and must be flashed/programmed with the specific machine's software using the New Holland Electronic Service Tool (EST) before the machine will operate.