Case IH 3861 – Engine Control Unit (ECU) / Electronic Diesel Control (EDC): eVGT power supply electrical failure

The engine controller has detected an electrical failure—specifically a voltage irregularity such as a short circuit, open circuit, or out-of-range voltage—in the power supply circuit dedicated to the Electronic Variable Geometry Turbocharger (eVGT) actuator.

• Steiger T4B
• 240 Series Axial-Flow Combines (7240, 8240, 9240)
• Magnum Series (250, 280, 310, 340, 380, Rowtrac)
• Steiger / Quadtrac Series
• Optum Series (Optum 300 CVT)
• T7 Series

1. 1

   Check battery and charging system to ensure system voltage is within the specified operating range.

2. 2

   Inspect the dedicated fuse for the eVGT actuator (often designated as F-203 on models like the Optum).

3. 3

   Test the eVGT actuator power relay using a multimeter to verify continuity and proper switching.

4. 4

   Visually inspect the wiring harness between the ECU, relay, and eVGT actuator for chafed wires, melted insulation, or pinch points.

5. 5

   Disconnect the eVGT actuator and inspect pins for corrosion, moisture, or bent terminals, and measure voltage at the supply pin with the key ON.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the battery to prevent electrical spikes during repair.

2. 2

   Replace Blown Fuses/Relays

   If the eVGT fuse is blown, replace it. If the relay fails the multimeter test, replace the relay. (Note: If a new fuse blows immediately upon key-ON, there is a dead short in the harness or the actuator itself).

3. 3

   Repair Wiring

   If harness damage is found during the diagnostic phase, repair the broken or shorted wires using OEM-approved waterproof splices, or replace the affected harness section.

4. 4

   Replace the eVGT Actuator

   If the fuse, relay, and wiring harness all test good (meaning proper voltage and ground are reaching the actuator connector), the eVGT actuator has suffered an internal electrical failure and must be replaced.

5. 5

   Reassembly and Clearing Codes

   Reconnect the battery. Connect the Case IH Electronic Service Tool (EST) to clear the inactive 3861 / 3498 fault codes.

6. 6

   Validation

   Start the engine and run it under load to ensure the turbocharger actuator responds correctly and the code does not return.