Case IH 517710-02 - UCM – UCM: Service brake pedal latch switch - Data erratic, intermittent, or incorrect (Circuit Fault)

The system has detected a circuit malfunction, erratic signal, or communication loss regarding the service brake pedal latch switch. This switch monitors whether the left and right brake pedals are physically locked together (latched) for safe road transport. If the controller receives an implausible or fluctuating signal from this switch, it logs this fault to prevent safety issues or improper trailer brake actuation.

• MAGNUM AFS Connect
• Case IH Magnum series
• Case IH Magnum AFS Connect
• Case IH Maxxum series
• Case IH Farmall series

1. 1

   Enter the tractor's diagnostic mode (e.g., the H9 Voltmeter Diagnostics menu) to view the live status of the switch on its assigned channel (often Channel 81). Verify the display toggles cleanly between 'latched' and 'not latched' when manually engaging and disengaging the pedal lock.

2. 2

   Locate the brake pedal latch switch (S33) near the brake pedal assembly in the cab. Inspect the switch mechanism for physical damage, debris, or misalignment preventing it from fully depressing.

3. 3

   Inspect the switch's electrical connector (C423 or in-line connectors X6/X7) for corrosion, pushed-out pins, or moisture.

4. 4

   Using a multimeter, check for continuity across the switch contacts when actuated. Test the wiring harness between the switch and the UCM for a short to ground, short to power, or an open circuit.

1. 1

   Preparation

   Park the tractor on a level surface, turn off the engine, remove the key, and disconnect the negative battery cable to prevent electrical shorts.

2. 2

   Access the Switch

   Remove any lower dash or steering column trim panels necessary to gain clear access to the brake pedal assembly inside the cab.

3. 3

   Disconnect

   Locate the S33 brake pedal latch switch on the pedal linkage. Unplug the electrical connector (C423).

4. 4

   Removal

   Unbolt or unclip the faulty switch from its mounting bracket. Take note of how the switch lever or plunger aligns with the pedal latch mechanism.

5. 5

   Installation

   Mount the new switch into the bracket.

6. 6

   Adjustment

   Adjust the switch position (if slotted) so that the plunger is fully actuated only when the left and right brake pedals are securely latched together.

7. 7

   Reassembly

   Reconnect the electrical connector and reinstall any removed trim panels. Reconnect the battery.

8. 8

   Verification

   Turn the key on, clear the inactive fault codes from the UCM, and verify the repair by checking the switch status in the diagnostic menu or test-driving the tractor to ensure the code does not return.