Case IH 520207-22 - VCM – UCM: Steering valve controller roading switch circuit fault

The roading switch is a safety lockout mechanism used to disable the auto-guidance steering valve when the tractor is traveling on public roads. This fault indicates that the controller has detected an electrical circuit malfunction (such as an open circuit, short, or missing voltage) and cannot verify the position of the roading switch, preventing the auto-guidance system from safely engaging.

• MAGNUM AFS Connect
• Magnum series
• Magnum 220 AFS Connect
• MX series
• Steiger series
• Steiger 335
• Steiger 385
• Steiger 435
• Steiger 485
• Steiger 535
• Steiger 620

1. 1

   Manually toggle the auto-guidance roading switch to see if cycling clears the error if the system kicked out or was left in an intermediate state.

2. 2

   Navigate to the ISOBus diagnostic page on the cab display to verify if the tractor controller recognizes the switch's physical position.

3. 3

   If equipped with a SmarTrax MD system, check the master roading switch located on the back of the MD unit (an 'MsSw Fail' or 'MsSw Off' error points here).

4. 4

   Inspect the Cab Main Wire Harness and roading switch connector (C656M) for loose pins, corrosion, or damaged wires.

1. 1

   Disconnect battery

   Turn off the machine and disconnect the battery to safely service the electrical circuit.

2. 2

   Access roading switch

   Access the upper console or headliner where the auto-guidance roading switch is mounted.

3. 3

   Disconnect connector

   Disconnect connector C656M from the roading switch.

4. 4

   Inspect wiring and terminals

   Inspect the wiring and the female terminals for signs of a short to ground, open circuit, or lack of voltage.

5. 5

   Test switch continuity

   Test the switch for continuity. If the switch fails to show proper continuity when toggled, remove it from the console panel.

6. 6

   Replace damaged terminals

   If the wiring harness terminals are damaged, splice in new OEM silver female terminals (see parts list below).

7. 7

   Install replacement switch

   Install the replacement roading switch and reconnect the C656M harness.

8. 8

   Restore power and verify

   Restore battery power, start the tractor, and engage the auto-guidance system. Verify that the steering settings page displays “GPS – ISO” (or a full green status indicator) and that the fault code has cleared.