John Deere 177.09 – SSU, RPT, PTF, or SST: CAN BUS Message Issue / Cannot Be Received

The control module logging the code is not receiving the expected CAN bus message containing the transmission/hydraulic oil temperature data from the transmission controller (such as the EPC, TCU, or PTA control software).

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6090MC
• 6100MC
• 6110MC
• 6090RC
• 6100RC
• 6110RC
• 6120-6520L
• 6230
• 6330
• 6430
• 7630
• 7730
• 7830
• 7930
• 8130
• 8230
• 8330
• 8430
• 8530
• 9230
• 9330
• 9430
• 9530
• 9630
• 8310RT
• 8335RT
• 8360RT
• 9660 CTS
• 9650 STS
• 9750 STS
• 310G backhoe
• 310J backhoe
• 310K backhoe
• 640G skidder
• 640H skidder

1. 1

   Restart the tractor to see if the code is triggered by a temporary CAN bus initialization glitch

2. 2

   Inspect fuses powering the transmission and steering control units (specifically F23, F6, or F35 depending on model)

3. 3

   Check the main Transmission Control Unit (TCU) or Engine Control Unit (ECU) for active companion codes (a direct sensor fault indicates a failed sensor rather than a CAN issue)

4. 4

   Visually inspect the CAN bus harness and connectors between the transmission controller and the SSU/RPT modules for corrosion, moisture, or backed-out pins

1. 1

   Power down machine

   Turn off the engine, remove the key, and locate the main fuse panel.

2. 2

   Test and replace fuses

   Test the relevant fuses (F23, F6, F35) with a multimeter. Replace any blown fuses and restart the machine to see if the code clears.

3. 3

   Repair CAN bus harness

   If fuses are good, use a multimeter to check the CAN High and CAN Low lines between the transmission controller and the module logging the fault. Repair any chafed wires or clean corroded connector pins with electrical contact cleaner.

4. 4

   Replace temperature sensor

   If companion codes indicate the transmission/hydraulic oil temperature sensor has failed: disconnect the electrical connector, place a drain pan underneath, unthread the old sensor, install the new OEM sensor with a properly seated O-ring, torque to factory specs, and reconnect the harness.

5. 5

   Clear codes and test

   Use a John Deere Service ADVISOR tool or equivalent scanner to clear the stored codes and test operate the machine to verify the CAN bus message is restored.