Case IH 520199-02 - VCM – UCM: Communication failure between the steering valve controller and the steering wheel sensor

The controller is not receiving the expected CAN bus messages or position data from the steering wheel angle sensor.

• MAGNUM AFS Connect
• Magnum AFS Connect 180
• Magnum AFS Connect 200
• Magnum AFS Connect 220
• Magnum AFS Connect 240
• Magnum AFS Connect 250
• Magnum AFS Connect 280
• Magnum AFS Connect 310
• Magnum AFS Connect 340
• Magnum AFS Connect 380

1. 1

   Visually inspect the CAN bus communication wiring harness between the Steering Valve Controller (SVC) and the Steering Wheel Sensor (SASA) for chafing, breaks, or pinch points.

2. 2

   Inspect the connectors at both the steering wheel sensor and the steering valve controller for corrosion, moisture intrusion, bent pins, or loose connections.

3. 3

   Verify that the steering wheel sensor is receiving proper operating voltage (typically 9-32 VDC) and has a solid ground connection.

4. 4

   Look for other UCM communication fault codes (such as 520200-02, 520201-02, or 520202-02). If multiple communication codes are present, the issue is likely a broader CAN bus failure rather than an isolated sensor failure.

1. 1

   Safely Prep the Machine

   Turn off the tractor, apply the parking brake, and disconnect the battery to prevent electrical shorts during testing.

2. 2

   Locate Components

   Locate the steering wheel sensor (mounted on the steering column) and the steering valve controller.

3. 3

   Disconnect and Isolate

   Disconnect the wiring harness connectors at both the sensor and the controller.

4. 4

   Continuity Testing

   Using a digital multimeter, perform a continuity test on the CAN High and CAN Low communication lines between the sensor and the controller.

5. 5

   Short Testing

   Test the communication lines for any short to ground or short to power.

6. 6

   Harness Repair

   If the wiring harness is damaged or fails the continuity/short tests, repair or replace the affected section of the harness.

7. 7

   Component Replacement

   If the wiring tests good, the fault is likely internal to the steering wheel sensor (failing to broadcast its CAN message). Replace the steering wheel sensor. (If the sensor is replaced and the issue persists, the steering valve controller itself may be at fault).

8. 8

   Reassembly and Clearing

   Reconnect the battery, clear the fault codes using a dealer diagnostic tool, and perform a test drive to verify the steering system operates correctly and the code does not return.