Case IH 3858 – Engine ECU (EDC - Electronic Diesel Control module): EVGT actuator position

The engine control module detects that the actual physical position of the turbocharger actuator does not match the commanded position, or when there is a CAN communication error preventing the actuator from reporting its position.

• 240 Series Axial-Flow Combines (7240, 8240, 9240)
• Magnum series
• Optum series (Optum 300 CVT)
• Puma
• Maxxum
• Farmall series

1. 1

   Verify active faults using the Electronic Service Tool (EST) to confirm if code 3858 is active, and look for related EVGT codes (e.g., 3598, 3861, 3864) that might pinpoint the issue.

2. 2

   Inspect the mechanical linkage connecting the EVGT actuator to the turbocharger. Ensure it is not disconnected, damaged, sticking, or blocked by soot/carbon buildup.

3. 3

   Check the dedicated power supply fuse and relay for the EVGT actuator (e.g., check the 20A Mini fuse F-203 on Optum models).

4. 4

   Test the wiring harness with the ignition OFF. Disconnect the engine harness from both the ECU and the EVGT actuator. Check for continuity, shorts to ground, and shorts to voltage on the power, ground, CAN High, and CAN Low lines. Test pin 4 of the actuator connector to chassis ground to ensure no voltage bleeds into the circuit.

1. 1

   Preparation

   Turn off the machine, remove the key, and disconnect the battery.

2. 2

   Access the Turbocharger

   Locate the EVGT actuator mounted on the side of the turbocharger assembly.

3. 3

   Disconnect Electricals

   Unplug the wiring harness connector from the EVGT actuator.

4. 4

   Remove Linkage

   Carefully remove the retaining clip/pin that secures the actuator linkage arm to the turbocharger's variable geometry mechanism.

5. 5

   Dismount Actuator

   Remove the mounting bolts securing the actuator to the turbocharger bracket and remove the faulty actuator.

6. 6

   Test Vane Movement

   Before installing the new actuator, manually move the turbocharger linkage arm back and forth. It must move completely freely. If it binds or grinds, the internal turbocharger vanes are seized with carbon, and the entire turbocharger must be cleaned or replaced.

7. 7

   Install New Actuator

   Mount the new EVGT actuator to the bracket and tighten the bolts. Reattach the linkage arm and secure it with the retaining clip.

8. 8

   Reconnect

   Plug in the electrical harness and reconnect the battery.

9. 9

   Calibration

   Connect the Case IH Electronic Service Tool (EST). You must run the EVGT actuator calibration/learn procedure. This allows the ECU to learn the new actuator's physical end-stops (Code 3866 will trigger if the system fails to learn).

10. 10

    Test

    Clear all fault codes and test run the engine under load to verify proper boost pressure.