Case IH 3858 – Engine Control Unit (ECU) / EDC (Electronic Diesel Control): CAN communication error between the ECU and the eVGT actuator

The Engine Control Unit (ECU) has lost Controller Area Network (CAN) data link communication with the electronic Variable Geometry Turbocharger (eVGT) actuator. Because of this communication loss, the ECU can no longer command the turbocharger vanes to adjust boost pressure, nor can it receive position or temperature feedback from the actuator's internal controller.

• Steiger T4B
• 240 Series Axial-Flow Combines
• Steiger series (350, 400, 425, 450, 475, 500, 525, 550, 600, 715)
• Quadtrac series (350, 400, 425, 450, 475, 500, 525, 550, 600, 715)
• Optum series (300 CVT)
• Magnum
• Puma
• Farmall

1. 1

   Connect the Electronic Service Tool (EST) to verify if DTC 3598 / 3858 is currently present and active.

2. 2

   Inspect the fuse dedicated to the eVGT actuator (often a 20A Mini fuse labeled F-203).

3. 3

   Visually inspect the engine wiring harness between the ECU and the eVGT actuator for chafing, melted wires, or disconnected/corroded pins.

4. 4

   Perform a voltage/short test: Turn ignition OFF, disconnect harness from ECU and eVGT actuator, remove eVGT relay, turn ignition ON, and check for voltage from harness side of eVGT connector (Pin 4) to chassis ground (should be no voltage).

5. 5

   Check the CAN-Receive-Frame lines for continuity and ensure there is no short circuit in the CAN wiring.

6. 6

   Check if the actuator is physically blocked, severely overheated, or has an internal CAN controller failure.

1. 1

   Power Down

   Turn off the machine, remove the key, and turn the battery disconnect switch to the OFF position before servicing the electrical system.

2. 2

   Fuse Replacement

   If the diagnostic checks revealed a blown eVGT power supply fuse, replace the fuse. Reconnect the battery, turn the key ON, and re-check for the code. If the fuse blows immediately, proceed to harness repair.

3. 3

   Harness Repair

   If the multimeter test showed a short to power, short to ground, or an open circuit in the CAN lines, locate the damaged section of the engine wiring harness. Repair the broken wires or replace the affected harness section.

4. 4

   Actuator Replacement

   If the wiring, fuses, and relays all test good, and the ECU is outputting the correct CAN signals, the fault lies within the eVGT actuator's internal electronic CAN controller. Remove the defective eVGT actuator (or the entire turbocharger assembly if the actuator is not serviced separately on your specific engine) and install the replacement.

5. 5

   Reassembly & Calibration

   Reconnect all electrical connectors and restore battery power.

6. 6

   Clear Codes

   Connect the EST, clear the inactive fault codes, and run the engine under load to ensure the turbocharger operates correctly and the communication code does not return.