Case IH 519070-04 - UCM – UCM: Rear hitch exterior top link switch left - invalid voltage

The control module is receiving a voltage signal from the left-hand rear fender switch (used to control the rear hitch top link) that falls below the expected operational range. This condition is typically caused by a short to ground in the wiring, a disconnected plug, moisture in the connector, or an internal failure of the switch itself.

• MAGNUM AFS Connect
• Magnum 220 AFS Connect
• Magnum 250 AFS Connect
• Magnum 280 AFS Connect
• Magnum 310 AFS Connect
• Magnum 340 AFS Connect
• Magnum 380 AFS Connect
• Magnum 400 AFS Connect

1. 1

   Inspect the left rear fender switch panel for physical damage

2. 2

   Locate the 3-pin electrical connector (X-403) on the back of the switch and check for moisture, dirt, or corroded pins

3. 3

   Trace the cab fender wiring harness back toward the UCM, looking for pinched wires, chafing against the fender frame, or exposed copper that could cause a short to ground

4. 4

   Disconnect the switch and use a multimeter to test for proper continuity when the switch buttons are actuated (if it reads open or shorted regardless of position, the switch has failed)

5. 5

   With the key on, probe the harness side of the connector to ensure the UCM is sending the correct reference voltage to the switch

1. 1

   Park the tractor on a level surface, turn off the engine, and engage the parking brake.

2. 2

   Turn off the master battery disconnect switch to prevent electrical spikes during repair.

3. 3

   Access the underside of the left rear fender to reach the exterior hitch switch assembly.

4. 4

   Depress the locking tab and disconnect the 3-pin AMP Superseal electrical connector from the top link switch.

5. 5

   Remove the retaining clips, locking nuts, or screws securing the switch housing to the fender panel.

6. 6

   Pull the faulty switch out of the fender mounting hole.

7. 7

   Insert the new switch assembly into the fender and secure it with the retaining hardware.

8. 8

   Apply a small amount of dielectric grease to the new switch terminals (if recommended by the OEM) and plug in the electrical connector until the locking tab clicks.

9. 9

   Turn the battery disconnect switch back on, power up the tractor, and clear the inactive fault codes.

10. 10

    Test the left fender top link controls to verify proper hitch operation.