John Deere 2005.09 – ECU, PTI, ICU, SCU / SCO, HCU, SCC: ACU Message Missing / Incorrect CAN BUS Message

Data transfer problem over the CAN bus network. The reporting control unit is not receiving required messages (such as torque speed select messages or general transmission information) from the ACU (Armrest Control Unit) / UIC (User Interface Controller).

• 5085E
• 5090E
• 5090EL
• 5100E
• 5085M
• 5100M
• 5100MH
• 5100ML
• 5115ML
• 5090M
• 5115M
• 7020 Series
• 7720
• 7820
• 7920
• 8030 Series
• 8130
• 8230
• 8330
• 8430
• 8530
• 9030 Series
• 9230
• 9330
• 9430
• 9530
• 9630
• 6M Series
• 6170M
• 7R Series
• 8R Series

1. 1

   Check system voltage to ensure batteries are fully charged, as low voltage or a failing alternator can cause CAN bus modules to drop offline

2. 2

   Check fuses powering the ACU or reporting module (commonly F13, F35, F24, F22, F30, or F6 depending on transmission and model)

3. 3

   Restart the vehicle by cycling the key to see if the code clears, which may indicate a transient voltage drop or software glitch

4. 4

   Inspect the wiring harness inside the right-hand armrest for chafing or breaks caused by physical movement

1. 1

   Verify Power and Ground

   Test the fuses mentioned above. If a fuse is blown, replace it. If it blows again immediately, you have a short to ground in the ACU circuit.

2. 2

   Inspect CAN Bus Wiring and Connectors

   Access the wiring harness leading into the Armrest Control Unit (ACU). Carefully inspect for pinched, chafed, or broken wires.

3. 3

   Test CAN Bus Functionality

   Use a multimeter or oscilloscope to check the CAN High and CAN Low lines at the ACU connector. You should see approximately 60 ohms of resistance across the CAN lines with the batteries disconnected. Check for continuity between the ACU and the ECU (or whichever module logged the code).

4. 4

   Repair Wiring

   If damaged wires are found in the armrest pivot point, repair them using appropriate CAN bus repair techniques (twisted pair, soldered/heat-shrinked), or replace the armrest harness entirely.

5. 5

   Update Software

   Ensure both the ACU and the reporting module (ECU) have the latest firmware updates via John Deere Service ADVISOR.

6. 6

   Replace the ACU

   If the wiring is perfectly intact, power and ground are present, and the CAN bus network is healthy but the ACU is still not broadcasting messages, the Armrest Control Unit itself has failed internally and must be replaced.

7. 7

   Reset and Verify

   Clear the codes from the ECU and restart the tractor to verify that communication with the ACU has been restored.