John Deere 002049.09 – ACU / BRC: CAN BUS Message Fault in Direct Drive Gear Shift Module

A communication breakdown has occurred on the Controller Area Network (CAN bus) between the Direct Drive Gear Shift Module and other control units. The .09 suffix indicates an abnormal update rate, meaning messages from the shift module are missing or not being received by the Armrest Control Unit (ACU) as expected. This fault can affect the proper operation of the gear shift system and is typically caused by wiring issues, intermittent connections, poor grounds, or a failure within the module itself.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R (2015-2021)

1. 1

   Restart the tractor to see if a simple power cycle resolves temporary communication glitches

2. 2

   Check for other active or stored fault codes, as communication faults often appear in groups

3. 3

   Inspect relevant fuses, specifically fuse F22, which is associated with ACU CAN message issues

4. 4

   Visually inspect wiring harnesses and connectors between the armrest controls and transmission for pinched wires, corrosion, or loose connections, paying close attention to ground wires

5. 5

   Perform a CAN bus resistance check with the battery disconnected: measure between CAN High (yellow) and CAN Low (green) at the diagnostic connector (expected: ~60 Ohms. 120 Ohms indicates an open circuit/missing resistor; 0 Ohms indicates a short)

6. 6

   Perform a CAN bus voltage check with the key on and engine off: CAN High should be 2.5-2.8V, and CAN Low should be 2.2-2.5V

1. 1

   Isolate the CAN bus fault

   If the CAN bus resistance is incorrect (e.g., 120 Ohms or 0 Ohms), use a split-half method by disconnecting a central module to split the network. Measure the resistance of each half to identify which section contains the open or short circuit.

2. 2

   Inspect and test the gear shift module

   If the main CAN wiring is intact, disconnect the Direct Drive Gear Shift Module and inspect its connector for corrosion or damage. Test the module's internal resistance or substitute it with a known good part.

3. 3

   Test for intermittent connections

   With the system powered on, wiggle the wiring harnesses and connectors to see if you can trigger the fault code. This helps pinpoint the exact location of a loose connection.

4. 4

   Consult a dealer for advanced diagnostics

   If the fault persists and the root cause is not apparent, have the machine serviced by a John Deere dealer using specialized diagnostic tools.