Case IH 2048 – Transmission Control Module (TRANS / TCU): Short Circuit in Bottom of Clutch (BOC) Switch or Relay

Indicates a short circuit in the lower part of the clutch pedal switch (often referred to as the "Bottom of Clutch" or BOC switch) or a short circuit in the bottom of the clutch relay (neutral relay). It can also mean the clutch pedal switch is adjusted too low or misadjusted, causing the system to read a continuous short or incorrect voltage when the pedal is depressed.

• Maxxum
• Farmall
• Steiger
• Quadtrac
• Magnum
• Puma
• T6000
• CX Series

1. 1

   Inspect the clutch pedal linkage and the Bottom of Clutch (BOC) switch for physical damage, looseness, or misadjustment (set too low on the bracket).

2. 2

   Disconnect the clutch pedal switch and clean the contacts with electrical contact cleaner to remove dust and debris buildup.

3. 3

   Inspect the wiring harness leading to the clutch pedal switch and the neutral/clutch relay for rubbed wires causing a short to ground.

4. 4

   Test the clutch pedal switch for continuity using a multimeter. It should operate as a normally open switch that closes when the pedal is fully depressed.

5. 5

   Test the clutch relay to ensure it is not stuck closed (shorted).

1. 1

   Disconnect Power

   Always disconnect the tractor's battery before servicing electrical transmission components.

2. 2

   Access the Switch

   Locate the clutch pedal safety switch, which is typically mounted near the clutch pedal linkage inside the cab or under the floor mat depending on the model.

3. 3

   Adjust or Replace

   If adjusting: Loosen the mounting nuts and adjust the switch height so it correctly contacts the pedal linkage only at the very bottom of the pedal's travel. If replacing: Unplug the wiring harness, unthread the old switch from its mounting bracket, and install the new switch.

4. 4

   Check the Relay

   If the switch tests fine, locate the transmission/neutral clutch relay in the fuse/relay panel and replace it if it is shorted.

5. 5

   Reassemble and Power Up

   Reconnect the battery and start the tractor to ensure the code is cleared. The tractor should not start unless the clutch is depressed, and it should not throw a transmission fault.

6. 6

   Transmission Calibration

   If the code caused shifting issues or if a new switch/potentiometer was installed, a transmission clutch calibration may be required. Calibration conditions: Transmission in neutral, engine running between 800–1200 RPM, parking brake engaged, transmission sump temperature around 75°C–80°C (167°F–176°F), and the machine completely stopped.