John Deere 103.02 – Engine Control Unit (ECU): Variable Geometry Turbo (VGT) Speed Signal Issue

The Engine Control Unit (ECU) has detected a problem with the speed signal from the variable geometry turbocharger (VGT). The computed turbo speed based on engine load does not match the actual measured speed, or the turbocharger speed signal is missing entirely. This discrepancy indicates a failure in the VGT speed sensor, its wiring circuit, or a mechanical issue preventing the turbo from reaching the expected speed.

• 5085E
• 5090E
• 5090EL
• 5100E
• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 5100M
• 8370R
• 9510R
• 9470RT
• 9520RT
• 9660
• 9760
• 9770
• 4930
• 544K
• 410E
• 540G-III

1. 1

   Check the VGT speed sensor and its wiring harness for damage, open circuits, or shorts to ground

2. 2

   Verify the VGT speed sensor is securely connected and not suffering from high resistance in the circuit

3. 3

   Inspect the turbocharger vanes and the VGT actuator for seizing or binding due to soot buildup

4. 4

   Cross-check related sensors, ensuring the MAP sensor is functioning correctly and not logging its own faults

1. 1

   Repair Wiring

   If the diagnostic checks reveal damaged wiring or corroded pins at the VGT speed sensor connector, repair the harness or replace the connector.

2. 2

   Replace VGT Speed Sensor

   If the wiring is intact but the signal remains invalid or erratic, remove and replace the VGT speed sensor located on the turbocharger housing.

3. 3

   Address Mechanical Binding

   If the turbo vanes are seized, you may need to replace the VGT actuator or the entire Variable Geometry Turbocharger assembly.

4. 4

   Recalibrate

   If the VGT actuator or the entire turbocharger is replaced, you must use John Deere diagnostic software (Service ADVISOR) to calibrate the new actuator to the engine.

5. 5

   Clear Codes and Test

   Clear the ECU codes and operate the engine under load to verify that the measured turbo speed matches the ECU's model and the code does not return.