John Deere PTQ002129.09 – ICU: ICU Message Missing

The system has detected a communication breakdown on the vehicle's CAN (Controller Area Network) bus, indicating that one or more electronic control units are not receiving expected messages from the Instrument Control Unit (ICU) within a specified timeframe. This signifies a failure in the transmission of critical data, which can be caused by a blown power supply fuse, damaged CAN bus wiring, or an internal failure of the ICU itself.

• 7630
• 7730
• 7830
• 7930
• 7720
• 7820
• 7920
• 7810
• 8130
• 8230
• 8330
• 8430
• 8530
• 9230
• 9330
• 9430
• 9530
• 9630

1. 1

   Restart the vehicle to see if the communication messages reset and the fault clears

2. 2

   Check fuse F28, which powers the ICU, to see if it is blown

3. 3

   Visually inspect the wiring harness and connectors connected to the ICU and the main CAN bus for signs of damage, corrosion, or loose connections

4. 4

   Measure CAN bus termination resistance with the system powered off (should be approximately 60 Ω between CAN High and CAN Low; 120 Ω indicates a missing terminating resistor)

5. 5

   Check CAN bus voltages with the system powered on and idle (both CAN High and CAN Low should be around 2.5V)

6. 6

   Isolate nodes by disconnecting controllers one by one to see if the fault clears, which would indicate a faulty node is bringing down the network

1. 1

   Perform diagnostic checks

   Perform all the diagnostic checks listed above.

2. 2

   Replace fuse and check for short

   If fuse F28 was blown, and the replacement fuse also blows, this indicates a short circuit in the ICU power supply that must be traced and repaired.

3. 3

   Repair CAN bus wiring

   If CAN bus wiring is found to be damaged, repair or replace the affected section of the harness.

4. 4

   Replace Instrument Control Unit (ICU)

   If all wiring and power supplies are confirmed to be good, the issue likely lies with the Instrument Control Unit (ICU) itself. Replacement of the ICU is the next logical step. This may require programming or calibration by a John Deere dealer to ensure compatibility with the specific tractor.