John Deere 002019.09 – ICU: ICU to SSU Communication Error

The Instrument Control Unit (ICU) is not receiving communication messages from the Steering Supervisor (SSU) controller. This loss of communication triggers a 'Repair at Earliest Convenience' alert on the display and directly affects the functionality of the AutoTrac™ assisted steering system.

• 7630
• 7730
• 7830
• 7930
• 8130
• 8230
• 8230T
• 8330
• 8330T
• 8430
• 8430T
• 8530

1. 1

   Restart the tractor to determine if the fault is a temporary communication glitch

2. 2

   Check fuse F23, which supplies power to the SSU controller (a blown fuse will cause a complete loss of power and communication)

3. 3

   Visually inspect the wiring harness and connectors leading to the SSU controller (typically located on the rear of the cab) for any signs of damage, corrosion, or loose connections

1. 1

   Verify power and ground

   Using a multimeter, check for unswitched power and a good ground connection at the SSU controller's electrical connector with the harness unplugged. A lack of power strongly indicates a wiring issue.

2. 2

   Trace the wiring harness

   If power is absent at the SSU connector, trace the wiring harness back towards its source. Inspect the harness behind the cab, where wires commonly become pinched, pierced, or corroded, leading to high resistance or a complete break.

3. 3

   Inspect bulkhead connectors

   The wiring for the SSU often passes through a bulkhead connector on the cab. Check for power on both sides of this connector to isolate the exact location of the fault.

4. 4

   Repair damaged wiring

   If a corroded or broken wire is found, cut out the damaged section and splice in a new piece of wire of the same gauge. Ensure the connections are securely soldered and protected with heat-shrink tubing to prevent future moisture intrusion.

5. 5

   Clear fault codes

   After the repair is complete, reconnect all connectors and start the tractor. Use the tractor's diagnostic system or a service tool to clear any active and inactive fault codes.

6. 6

   Verify repair

   With the engine running, check that the ICU 002019.09 code does not reappear and that the SSU controller is back online and communicating with the ICU.