New Holland UCM 5313 – UCM: Enhanced High-Flow Auxiliary Option: EHF Enable Switch Short to Power

The control module is detecting an abnormally high voltage on the circuit for the Enhanced High-Flow (EHF) enable switch, meaning the signal wire is shorted to a power source (such as a 12V line).

• L220
• L223
• L225
• L230
• C227
• C232
• C238
• L330
• C332

1. 1

   Inspect the EHF Enable Switch for physical damage, sticking, or liquid intrusion that could cause an internal short.

2. 2

   Disconnect the switch and inspect the wiring harness connector for corrosion, bent pins, or moisture.

3. 3

   Use a multimeter to test the switch for internal continuity, verifying it is not internally shorted across the power and signal pins when in the neutral/off position.

4. 4

   Trace the wiring harness from the switch back to the UCM, looking for pinch points, chafed insulation, or melted wires where the signal wire might contact a 12V power supply.

1. 1

   Power Down

   Turn off the machine, remove the key, and disconnect the negative battery cable to prevent electrical damage during testing.

2. 2

   Access the Switch

   Remove the retaining screws for the side console panel to access the rear of the rocker switches.

3. 3

   Isolate the Circuit

   Disconnect the wiring harness from the EHF Enable Switch.

4. 4

   Perform Multimeter Testing

   Test the switch itself. If it fails the continuity test (showing a short to power internally), the switch must be replaced. If the switch is good, probe the signal wire on the harness side. Reconnect the battery temporarily and turn the key to the ON position (engine off). Check for voltage on the signal wire. If 12V is present when it shouldn't be, there is a short in the harness.

5. 5

   Repair the Harness

   If a short is found in the wiring, trace the harness back to the UCM, locate the chafed/damaged section, splice in new wire using weather-sealed heat shrink connectors, and re-loom the harness.

6. 6

   Reassembly and Clearing

   Reconnect the switch, reinstall the console panel, and reconnect the battery. Turn the machine on, clear the inactive fault codes from the UCM, and test the EHF system to ensure the code does not return.