John Deere 641.31 – ECU: VGT Actuator Supply Voltage Fault

The Variable Geometry Turbocharger (VGT) actuator has detected that its supply voltage is out of the specified high range. This condition is typically caused by a malfunctioning voltage regulator, a short or issue in the electrical supply wiring, or an internal electrical fault within the actuator itself. As a protective reaction, the system may limit or disable turbocharger functionality to prevent damage.

• 5085E
• 5090E
• 5090EL
• 5100E
• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 5085M
• 5100M
• 5100MH
• 5100ML
• 5115ML
• 9470RT
• 9520RT
• 9570RT
• 6090MC
• 6090RC
• 6100MC
• 6100RC
• 6110MC
• 6110RC
• 7830
• 8370R
• 9510R
• 7180
• 7280
• 7380
• 7480
• 7580
• 7780
• 7980

1. 1

   Inspect Voltage Supply & Wiring: Check the wiring harness and connectors leading to the VGT actuator for any signs of damage, corrosion, chafing, or disconnection.

2. 2

   Measure Circuit Voltage: Use a multimeter to measure the supply voltage at the actuator connector with the key ON (engine off). Verify if the voltage is actually spiking out of range (which points to a machine voltage regulator/alternator issue) or if the wiring is shorted to a high power source.

3. 3

   Mechanical Verification: Ensure the mechanical linkage and the turbocharger's variable geometry vanes are not seized. A physically jammed turbo can sometimes cause the actuator motor to over-amp or behave erratically, though this specific code points strictly to supply voltage.

1. 1

   Resolve Wiring Issues

   If the diagnostic checks reveal damaged wires or a short to a high-voltage source, repair or replace the affected section of the engine wiring harness.

2. 2

   Replace the Actuator

   If the harness provides the correct voltage but the actuator still registers a high-voltage internal fault, the VGT actuator's internal circuit board has likely failed and the actuator must be replaced.

3. 3

   Install the New Actuator

   Mount the new VGT actuator to the turbocharger using the provided installation kit.

4. 4

   Calibrate the Actuator

   A new VGT actuator must be calibrated to the turbocharger using John Deere Service ADVISOR or a compatible aftermarket heavy-duty diagnostic tool (like Cojali/Diesel Laptops).

5. 5

   Clear Codes and Test

   Reset the ECU to clear the 000641.31 code. Run the engine and perform a system test to ensure the turbocharger functions correctly and the code does not return.