Case IH 735-13 - DEC – Transmission Control Unit (TCU) / Transmission Controller: Transmission C2 clutch solenoid out of calibration

The fault indicates that the Transmission Control Unit has failed to successfully calibrate the C2 clutch. During the calibration process, the controller measures the fill time, torque curve, and pressure required to engage the clutch. If the engagement point or electrical feedback falls outside the programmed target values, the calibration fails. This can be caused by a faulty proportional solenoid (FEMA valve), electrical wiring issues, incorrect hydraulic pressure, or internal mechanical wear/leaks in the C2 clutch pack.

• MAGNUM AFS Connect
• Case IH MXU series
• MXU115
• Maxxum 5120
• Maxxum 5130
• Maxxum 5140
• Maxxum 5150
• Magnum

1. 1

   Verify the transmission fluid level and condition.

2. 2

   Check for related active electrical circuit codes, such as C2 clutch solenoid open circuit (E43) or short circuit, which would prevent calibration.

3. 3

   Swap the C2 clutch solenoid (FEMA valve) with the C1 clutch solenoid. If the calibration error or shifting issue moves to a different gear block, the solenoid is faulty.

4. 4

   Check the voltage and electrical connector at the C2 solenoid to ensure the TCU is sending the correct PWM signal.

5. 5

   Apply air or hydraulic pressure to the C2 clutch pressure pipe port. Listen for air escaping in the forward gearbox section or check for pressure drops, which indicates internal leaks (e.g., leaking jump tubes or piston seals).

6. 6

   Perform a C1/C2 clutch drag and element slip check to determine if the internal clutch discs are excessively worn.

1. 1

   Warm Up

   Operate the tractor to heat the transmission hydraulic oil to the specified operating temperature.

2. 2

   Attempt Calibration

   Enter the transmission calibration mode via the tractor's instrument cluster or Electronic Diagnostic Tool (EDT). Follow the prompts to calibrate the C2 clutch (this typically involves setting engine RPM, depressing the clutch pedal, and holding the upshift/downshift buttons).

3. 3

   Inspect Wiring

   If calibration fails, locate the C2 clutch solenoid on the transmission control valve block. Inspect the wiring harness and the female electrical connector for damage, corrosion, or loose pins.

4. 4

   Replace Solenoid

   If the solenoid swap test (Diagnostic Check #3) proved the valve is defective, replace the C2 clutch solenoid with a new OEM unit.

5. 5

   Internal Rebuild (if necessary)

   If the electrical checks and solenoid are good, but the hydraulic test shows pressure loss, the internal C2 clutch is too worn to calibrate or has blown seals. The tractor must be split to access the forward gearbox section. Remove the C1/C2 clutch assembly and replace the worn clutch friction discs, seals, and jump tubes.

6. 6

   Final Calibration

   Reassemble the tractor, refill with Case IH Akcela Nexplore fluid, and perform a full transmission calibration.