Case IH 519068-02 - UCM – UCM: Rear hitch exterior inching switch left circuit fault

The control module is detecting an abnormally low voltage signal from the left rear fender switch, which is used by the operator to incrementally raise or lower (inch) the 3-point hitch from outside the cab. The '-02' failure mode indicator specifically designates a 'low voltage' (tensão baixa) or short-to-ground condition in the circuit.

• MAGNUM AFS Connect
• Steiger AFS Connect
• Optum series

1. 1

   Visually inspect the left rear fender exterior hitch switch (inching switch) for physical damage, sticking buttons, or water ingress.

2. 2

   Trace the wiring harness from the left fender switch back to the UCM. Look for chafing, pinched wires, or exposed copper that could be causing a short to ground.

3. 3

   Disconnect the switch and use a multimeter to check the connector for the proper reference voltage from the UCM.

4. 4

   Test the switch itself for internal shorts. There should be no continuity across the contacts when the switch is in the neutral/unpressed position.

5. 5

   Inspect the UCM connector and the switch connector for bent pins, corrosion, or pushed-out terminals.

1. 1

   Prepare machine

   Park the tractor on a level surface, lower the 3-point hitch completely (if possible), turn off the engine, and disconnect the battery to prevent electrical shorts during repair.

2. 2

   Locate switch

   Locate the left rear exterior inching switch assembly on the left rear fender.

3. 3

   Access switch housing

   Reach behind the fender panel or remove the plastic access panel covering the switch housing.

4. 4

   Disconnect switch

   Disconnect the electrical plug-in connector from the switch assembly.

5. 5

   Remove faulty switch

   If the diagnostic tests proved the switch is internally shorted, remove the retaining hardware (usually a rubber boot, lock nut, or mounting screws) and pull the old switch out of the fender.

6. 6

   Install new switch

   Install the new switch assembly, ensuring the switch diagram/orientation is in the correct position (facing inward toward the rockshaft).

7. 7

   Reinstall weather boot

   Reinstall the rubber weather boot to prevent future water ingress.

8. 8

   Repair harness and reconnect

   Reconnect the wiring harness. If the harness was damaged rather than the switch, splice and heat-shrink the damaged wires or replace the fender harness section.

9. 9

   Clear codes

   Reconnect the battery, turn the key on, and clear the UCM fault codes via the AFS Pro monitor or diagnostic service tool.

10. 10

    Test switch

    Test the left exterior hitch switch to confirm the 3-point hitch raises and lowers correctly without throwing the code.