Case IH 520207-25 - VCM – VCM / UCM: Circuit failure of the steering valve controller roading switch

Indicates a circuit/wiring failure for the steering valve controller roading switch. The roading switch is a safety lockout used to toggle the tractor's steering system between On-Road and Off-Road modes, and must be in the off-road position for autoguidance to engage.

• MAGNUM AFS Connect
• Case IH AFS Connect Magnum series
• Case IH AFS Connect Steiger / Quadtrac series

1. 1

   Verify Switch Position: Ensure the roading switch (typically located on the headliner or upper console) is not physically stuck or accidentally left in the 'On-Road' position.

2. 2

   Display Diagnostics: Go to the ISOBUS diagnostic page on the Pro 1200 display. Select 'Tractor settings' and scroll to the steering page. Check if the steering mode is registering as on-road or off-road.

3. 3

   Harness & CAN Check: Inspect the wiring harness leading to the roading switch for open circuits, shorts, or disconnected cables. Also, verify there are no CAN communication errors between the steering controller and the vehicle controller.

1. 1

   Monitor switch state

   Turn on the tractor and navigate to the Pro 1200 display's ISOBUS diagnostic page to monitor the roading switch state.

2. 2

   Command off-road mode

   Depress the top of the roading switch to command 'off-road' mode. If the display does not update (the 'status cake' icon does not show the steering wheel as ready), power down the machine.

3. 3

   Access switch panel

   Access the roading switch panel in the headliner/console.

4. 4

   Disconnect connector

   Disconnect the 10-cavity electrical connector at the back of the roading switch.

5. 5

   Inspect terminals

   Inspect the female terminals for corrosion, pushed-out pins, or wire chafing (a common cause of the -25 circuit failure code).

6. 6

   Test switch continuity

   Test the switch for continuity across its toggled states. If the switch is internally faulty, replace it.

7. 7

   Repair wiring harness

   If the switch tests good, repair the wiring harness back to the VCM/UCM.

8. 8

   Reconnect and clear faults

   Reconnect the switch, power on the tractor, and clear any active steering faults.

9. 9

   Perform calibration

   If necessary, perform a Wheel Angle Sensor and Steering Valve calibration to restore autoguidance functionality.