John Deere 84.05 – CCU: Wheel Speed Sensor Open Circuit Low Amps

The control module has detected a break in the electrical circuit, a disconnected sensor, or a current draw that is lower than the acceptable threshold for the wheel speed sensor.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6090MC
• 6090RC
• 6100MC
• 6100RC
• 6110MC
• 6110RC
• 5075M
• 5090M
• 5095M
• 5100M
• 5115M
• 5125M
• 8225R through 8345R
• 8R 340 to 8R 540
• 8RX 410 to 8RX 540
• 8100-8600 series harvesters
• 643L-III
• 843L-III

1. 1

   Inspect the wheel speed sensor wiring harness for broken wires, and check the connectors for looseness, dirt, or corrosion. Clean all electrical connections thoroughly, as corrosion can cause intermittent open-circuit readings.

2. 2

   Use a digital multimeter (ohmmeter) or continuity tester to check the wiring harness between the sensor and the CCU. Wiggle the wires during testing to check for intermittent breaks.

3. 3

   Connect a diagnostic scan tool (such as John Deere Service Advisor). Monitor the wheel speed sensor PIDs in real-time while driving the tractor at a steady speed. Verify if the live speed reading matches the ground speed or if it drops to zero/behaves erratically.

4. 4

   If the sensor is reading erratically, check the air gap between the sensor tip and the tone ring. The typical adjustment requires a 0.5 mm to 1.5 mm gap, which is sometimes adjusted via washer shimming or threading.

1. 1

   Locate the Sensor

   Find the faulty wheel speed sensor on the affected wheel hub, axle, or hydrostatic motor housing.

2. 2

   Remove the Old Sensor

   Disconnect the electrical harness. Back off the locking nut and pull the O-ring back against the locking ring. Unthread and remove the sensor from the housing.

3. 3

   Install the New Sensor

   Thread the new sensor in by hand until you feel the tip physically make contact with the tone ring inside the hub/motor.

4. 4

   Set the Air Gap

   Once it touches the tone ring, back the sensor out exactly 1/2 to 1 full turn to establish the correct air gap (approx. 0.5 - 1.5 mm).

5. 5

   Secure the Sensor

   If equipped with a sensor protector bracket, test the fit and install it. Tighten the locking ring/nut into the housing to compress the O-ring. Caution: Do not overtighten the locking nut.

6. 6

   Reconnect and Clear Codes

   Reconnect the electrical harness. Use John Deere Service Advisor or a compatible scan tool to clear the stored 000084.05 fault code from the CCU.

7. 7

   Test Drive

   Drive the machine and monitor the live data to ensure the new sensor is accurately tracking ground speed.