Case IH 517710-03 - UCM – UCM: Service brake pedal latch switch voltage high

The control module has detected that the voltage on the service brake pedal latch switch circuit is higher than the expected normal operating range. This condition typically indicates a short to power (B+) in the wiring harness or an open circuit on the ground/return side of the switch.

• MAGNUM AFS Connect
• Steiger AFS Connect
• Optum
• Puma

1. 1

   Inspect the service brake pedal latch switch (located on the brake pedal assembly in the cab) and its electrical connector for physical damage, corrosion, or loose pins.

2. 2

   Trace the wiring harness between the brake pedal latch switch and the UCM. Look for chafed wires causing a short to a 12V power source, or a broken wire causing an open ground circuit.

3. 3

   Use a multimeter to measure the voltage at the switch connector to verify the high voltage condition.

4. 4

   Test the switch itself for proper continuity. The state should change cleanly when the brake pedals are latched together versus when they are unlatched.

1. 1

   Turn off the tractor ignition and disconnect the battery to ensure safety and prevent further electrical shorts.

2. 2

   Locate the service brake pedal latch switch on the brake pedal assembly inside the cab.

3. 3

   Disconnect the electrical connector from the switch.

4. 4

   If the diagnostic checks revealed a wiring issue (short to power or open ground), repair or replace the damaged section of the wiring harness.

5. 5

   If the wiring is intact but the switch failed the continuity test, remove the mounting hardware for the faulty brake pedal latch switch and install a new OEM replacement switch.

6. 6

   Reconnect the electrical connector to the switch and reconnect the tractor's battery.

7. 7

   Turn on the ignition and use the tractor's diagnostic display monitor (e.g., AFS Pro 1200) to clear the inactive fault codes.

8. 8

   Test the operation by physically latching and unlatching the brake pedals to ensure the UCM registers the state change and the 517710-03 fault code does not return.