John Deere 524221.09 – SSU / SST: Vehicle Yaw Rate Message Missing

The Steering System Control Unit (SSU) is not receiving the machine yaw rate message from the GPS receiver over the CAN bus network. The yaw rate measures the machine's rotational speed around its vertical axis, which is a critical data point for the AutoTrac system to make accurate steering adjustments. When this communication is missing, the steering valve cannot be commanded correctly, rendering the AutoTrac system inoperable.

• 7630
• 7730
• 7830
• 7930
• 8130
• 8230
• 8230T
• 8330
• 8330T
• 8430
• 8430T
• 8530
• 9230
• 9330
• 9430
• 9530
• 9630
• 9870 STS

1. 1

   Verify if the fault is active by clearing stored codes on the display and operating the vehicle to see if 524221.09 reappears.

2. 2

   Check GPS receiver visibility on the GreenStar™ display CAN bus menu to see if the receiver is detected.

3. 3

   Visually inspect all physical connections, including the main connector at the StarFire™ unit and the ISO plug at the back of the tractor, for corrosion and secure seating.

4. 4

   Examine the GPS receiver wiring harness for physical damage, cracks from sun exposure, chafing, pinching, or moisture intrusion.

5. 5

   Verify system power by checking fuse F23 (for SSU), the main fuse panel, and testing for power and ground at the receiver's 4-pin harness connector.

1. 1

   Address basic connection issues

   Clean any corroded connectors, repair minor wire damage, and replace any blown fuses found during inspection. Clear fault codes and re-test the system.

2. 2

   Perform a component restart

   Power down the tractor and receiver. Disconnect the receiver harness from the machine to ensure a full power-off state, then reconnect and restart to clear temporary glitches.

3. 3

   Calibrate Terrain Compensation Module (TCM)

   If the fault is intermittent or accompanied by poor AutoTrac™ performance, recalibrate the TCM (especially if the receiver was recently reinstalled).

4. 4

   Replace wiring harness

   If the wiring harness shows significant damage such as brittle or cracked insulation, replace it to ensure reliable communication.

5. 5

   Replace GPS receiver or SSU

   If communication fails completely or the receiver constantly reboots, replace the StarFire™ receiver. If fault code SSU 000629.12 is also present, replace the Steering System Control Unit (SSU).