Case IH 1955-04 - UCM – UCM: Aux Valve 4 Port Flow Command - Voltage Below Normal, Or Shorted To Low Source

Rear Pilot Head #4 (the electro-hydraulic actuator for rear remote valve #4) is reporting a supply voltage that is too low or has a short to ground in its supply circuit.

• MAGNUM AFS Connect
• Magnum Series Tractors
• Steiger Series Tractors
• Axial-Flow Combines
• Puma Series Tractors

1. 1

   Check the wiring harness and connectors between the UCM and the Rear Pilot Head #4 for abrasion, nicks, cuts, or improper clamping

2. 2

   Monitor the active diagnostic code screen on the electronic service tool while pulling or wiggling the harnesses and connectors to check for intermittent shorts

3. 3

   Disconnect the harness at the #4 pilot head and use a multimeter to verify if the correct supply voltage is reaching the connector from the UCM

4. 4

   Test the supply wire for continuity to ground to confirm if a short exists in the harness

1. 1

   Disconnect Power

   Turn off the machine and disconnect the electrical connector at the Rear Pilot Head #4.

2. 2

   Inspect Connectors

   Check the connector pins on both the harness side and the pilot head side for corrosion, moisture, pushed-back pins, or damage. Clean or replace pins as necessary.

3. 3

   Trace and Repair Wiring

   If voltage is low at the connector, trace the wiring harness back to the UCM. Look for physical damage or chafing against the tractor chassis. Repair any damaged wires using solder and heat shrink, or replace the affected harness section.

4. 4

   Replace the Pilot Head

   If the wiring and connectors are completely intact, the voltage from the UCM is correct, and the code remains active, the fault is likely an internal short within the Rear Pilot Head #4 solenoid/actuator itself. Remove the mounting screws and replace the pilot head assembly.

5. 5

   Verify Repair

   Reconnect all components, clear the fault codes using the electronic service tool, and operate the #4 rear remote to verify the repair.