Case IH 2259-04 - UCM – UCM: Rear pilot head #8 reporting supply voltage low.

The controller is detecting lower-than-expected voltage on the circuit supplying the #8 rear remote valve pilot head. A shorted pilot head can pull down the voltage, causing the specific remote valve to become non-functional, and it can sometimes crash the CAN bus communication, disabling the other remote valves on the stack.

• MAGNUM AFS Connect
• Steiger / Quadtrac 350
• Steiger / Quadtrac 370
• Steiger / Quadtrac 400
• Steiger / Quadtrac 420
• Steiger / Quadtrac 450
• Steiger / Quadtrac 470
• Steiger / Quadtrac 500
• Steiger / Quadtrac 580
• Magnum 200
• Magnum 210
• Magnum 225
• Magnum 280
• Magnum 290
• Puma 165
• Puma 180
• Puma 185
• Puma 195
• Puma 200
• Puma 210
• Puma 220
• Puma 225
• Puma 240
• Optum 270
• Optum 300

1. 1

   Isolate the Short: Unplug the electrical connector specifically at the #8 pilot head. If the other remote valves suddenly come back online and function normally, the #8 pilot head has an internal short that is killing the CAN bus/power circuit and must be replaced.

2. 2

   Inspect the Harness: Check the wiring harness and connector going into the #8 pilot head for damaged pins, corrosion, or water ingress, which can cause a low voltage reading.

3. 3

   Check UCM Power: Verify the main battery voltage and the power supply grounds going to the UCM, as a general UCM power drop can trigger localized low-voltage codes.

1. 1

   Access the Valve Stack

   Locate the rear remote valve stack at the back of the tractor. Identify the #8 valve section.

2. 2

   Remove the Faulty Pilot Head

   Disconnect the electrical harness from the #8 pilot head. Remove the mounting screws (typically M5 x 20mm hex socket screws) securing the pilot head to the main valve body.

3. 3

   Install the New Pilot Head

   Place the new pilot head assembly onto the valve body, ensuring the O-rings/seals are properly seated. Torque the mounting screws to spec and reconnect the electrical harness.

4. 4

   Valve Calibration & Renumbering

   You cannot simply plug and play a new pilot head. Once installed, you must use the tractor's display monitor (e.g., HK Menu Screen, Channel 1) or the Case IH Electronic Service Tool (EST) to perform a "Valve Calibration" and reassign/renumber the valves. If you do not reassign the valves, the UCM will not recognize the new pilot head and it will remain non-functional.