Case IH U40 – Transmission Control Module (TCM) / Transmission ECU: Synchroniser did not move toward forward, even at maximum pressure.

The transmission control system commanded the synchroniser to engage the forward position and applied maximum hydraulic pressure, but the synchroniser failed to physically move into the correct position.

• Maxxum
• MX170
• Farmall 40
• Farmall 45
• Farmall 50
• Puma series
• Puma 140
• Puma 210
• Steiger series
• MX/TG series
• Maxxum series

1. 1

   Remove the transmission top cover and physically watch the synchroniser movement while the tractor attempts to shift to detect mechanical binding or lack of movement.

2. 2

   Enter diagnostic mode H9 and use a voltmeter to verify if the synchroniser potentiometer signal is within the expected voltage range.

3. 3

   Visually inspect the forward and reverse solenoid connectors to ensure they have not been accidentally swapped during previous maintenance.

4. 4

   Check the synchroniser potentiometer to see if it has been painted over during factory production, which is a known issue causing signal faults.

1. 1

   Swap/Correct Solenoid Connectors

   If the forward and reverse solenoid connectors are swapped, plug them into their correct respective solenoids.

2. 2

   Test the Forward Solenoid

   Test the forward solenoid for electrical faults (check for proper voltage delivery and verify resistance across the solenoid, typically around 8 to 9 ohms). If the solenoid is faulty, replace it.

3. 3

   Check Transmission Oil Pressure

   Verify that there is adequate hydraulic oil pressure reaching the synchroniser circuit. If there is no oil pressure to shift the synchroniser, troubleshoot the transmission hydraulic pump, shuttle valve assembly, or pressure switches.

4. 4

   Inspect/Replace the Potentiometer

   If the synchroniser potentiometer or its connector has been damaged, or if it is restricted by production paint, clean the connections or replace the potentiometer.

5. 5

   Free Up the Synchroniser Assembly

   If the electrical components and pressures are fine, the synchroniser assembly itself may be very tight or sticky. Attempt to repeat the transmission calibration procedure to free up the synchroniser. If it remains stuck, the synchroniser assembly will require mechanical repair or replacement.