Case IH 1931-03 - UCM – UCM: Rear Pilot Head #2 supply voltage high

The UCM detects a voltage on the Rear Pilot Head #2 circuit that exceeds the maximum allowable threshold. This is typically caused by an internal short inside the pilot head solenoid, a short-to-power in the wiring harness, or a failure that is backfeeding voltage and disrupting the CAN bus network.

• MAGNUM AFS Connect
• Puma 185
• Puma 185CVT
• Puma 200
• Puma 220
• Puma 220CVT
• Puma 240CVT
• Optum 270
• Optum 300
• Steiger 350
• Steiger 400
• Steiger 450
• Steiger 500
• Steiger 580
• Quadtrac 370
• Quadtrac 420
• Quadtrac 450
• Quadtrac 470
• Quadtrac 500
• Magnum 210
• Magnum 280

1. 1

   Perform the Unplug Test: Locate the #2 rear remote valve pilot head and unplug its electrical connector.

2. 2

   Check CAN Bus / System Status: Turn the key on. If the rest of the remote valves come back online and system communication is restored, the pilot head has an internal short that is disrupting the CAN bus.

3. 3

   Harness Check: If unplugging the pilot head does not clear the high voltage state, inspect the wiring harness between the UCM and the pilot head for a short-to-power (e.g., a chafed wire touching a 12V source).

1. 1

   Power down the machine and relieve hydraulic pressure from the rear remote valves.

2. 2

   Disconnect the electrical harness from Rear Pilot Head #2.

3. 3

   Unbolt and remove the faulty pilot head valve assembly from the remote valve stack.

4. 4

   Install the new pilot head valve assembly and torque to OEM specifications.

5. 5

   Reconnect the electrical harness.

6. 6

   Perform a hydraulic valve calibration procedure via the tractor's AFS Pro display/diagnostic tool.

   The UCM must learn the parameters of the new pilot head. The system will not operate correctly until calibrated.