John Deere 84.09 – RPT, SSU, SST, SFA: CAN BUS Message Fault - Wheel Speed Message Missing

This code indicates that the control module has lost communication with the wheel speed sensor over the vehicle's Controller Area Network (CAN) bus. The module is not receiving the expected travel speed data, which is required for various automated functions (like PTO engagement, AutoTrac, or transmission shifting).

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6110M
• 6120M
• 6125M
• 6130M
• 6140M
• 6145M
• 6155M
• 6175M
• 6195M
• 7R Series
• 8R/8RT Series
• 9R/9RT Series

1. 1

   Restart the Vehicle: Restart the tractor to see if the code returns, as CAN bus timeouts can occasionally be intermittent.

2. 2

   Check for Accompanying Codes: Look for other active codes (such as 000084.14 or 000084.31) which indicate a direct hardware failure of the wheel speed sensor itself rather than just a CAN bus timeout.

3. 3

   Visual Inspection: Inspect the batteries, alternator, and main chassis wiring harnesses for accumulated debris, corrosion, or physical damage.

4. 4

   Check Fuses: Verify the fuses supplying the CAN bus and the RPT module (often F23 or F35, depending on the specific model's load center).

5. 5

   Harness Integrity: Check the CAN bus wiring harness connecting the RPT module (located at the rear of the cab/chassis) to the main vehicle bus.

1. 1

   Clear and Verify

   Clear the fault codes and operate the tractor. If 000084.09 returns immediately, proceed to hardware checks.

2. 2

   Inspect the Wheel Speed Sensor

   Locate the wheel speed sensor (typically mounted on the transmission housing or rear axle). Disconnect the sensor and inspect the pins for corrosion, moisture, or pushed-back terminals.

3. 3

   Test CAN Bus Resistance

   With the tractor powered off and the battery disconnected, measure the resistance across the CAN High and CAN Low pins at the RPT module connector. It should read approximately 60 ohms. If it reads 120 ohms, one of the CAN terminating resistors or a segment of the bus is broken.

4. 4

   Check Module Power/Ground

   Probe the RPT module connector to ensure it is receiving proper unswitched battery voltage, switched ignition voltage, and a solid ground.

5. 5

   Software/Module Replacement

   If the wiring harness, CAN bus integrity, and wheel speed sensor all test good, the RPT module may have an internal fault or require a software flash. (OEM manuals advise having a John Deere dealer perform module programming or replacement).