John Deere 103.05 – Engine Control Unit (ECU): Variable Geometry Turbo Speed Sensor Circuit High Resistance

The Engine Control Unit (ECU) has detected high electrical resistance or an open circuit in the Variable Geometry Turbocharger (VGT) speed sensor wiring. This condition disrupts the signal transmission from the sensor to the controller, preventing the ECU from accurately monitoring turbocharger rotational speed, which is necessary to control boost pressure and optimize engine performance. This leads to a 'Turbo Speed Error' or 'Turbocharger speed sensor circuit fault'.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 5085M
• 5095M
• 5100M
• 5085E
• 5090E
• 5100E
• 9430
• 9530
• 9630
• 9570 STS
• 9660 STS
• 9760 STS
• 9770 STS
• 4930

1. 1

   Inspect the turbo speed sensor wiring harness and connectors for visible damage, corrosion, or loose pins.

2. 2

   Use a multimeter to check for continuity and resistance on the sensor circuits (cc# 5417 and cc# 5435) from the sensor connector back to the ECU. Look for a broken wire or a short to ground.

3. 3

   Test the resistance of the turbo speed sensor itself to determine if the internal coil is open or out of specification.

1. 1

   Disconnect Power

   Disconnect the machine's battery to ensure safety and prevent electrical shorts.

2. 2

   Locate the Sensor

   Locate the Variable Geometry Turbo Speed Sensor mounted on the turbocharger assembly.

3. 3

   Harness Repair

   If the diagnostic checks revealed a broken wire or corroded connector in circuits 5417/5435, repair the wiring harness or replace the connector pigtail.

4. 4

   Remove the Sensor

   If the wiring is intact but the sensor failed the resistance test, disconnect the electrical connector, remove the mounting bolt(s) securing the sensor, and carefully extract the old sensor from the turbocharger housing.

5. 5

   Install the New Sensor

   Insert the new turbo speed sensor (or sensor kit) into the housing and torque the mounting hardware to OEM specifications.

6. 6

   Reconnect

   Reconnect the electrical harness to the sensor.

7. 7

   Clear Codes

   Reconnect the battery, start the engine, and use a John Deere Service Advisor diagnostic tool to clear the ECU codes and verify that the turbo speed is now reading correctly.