Case IH 2676 (517971.12) - DEC – Transmission Control Unit (TCU): Synchro R1 uncommanded disengagement

The transmission controller detected that the Synchro R1 (a synchronizer/solenoid assembly responsible for a specific reverse range) disengaged or lost its engaged position without receiving a command to do so from the controller. This is typically caused by a loss of hydraulic pressure, a failing solenoid, a faulty position sensor, or a wiring issue dropping the signal.

• VESTRUM CVX
• Case IH Magnum series tractors equipped with the CVT
• Case IH Magnum 220 CVT (NA) (4/14-)

1. 1

   Inspect the wiring harness leading to the Synchro R1 Solenoid for damage, corrosion, or loose pins at connector X-644

2. 2

   Inspect the wiring and connector X-533 for the Synchro F2-R1 Sensor, as a faulty sensor can falsely report an uncommanded disengagement

3. 3

   Verify transmission hydraulic charge pressure, as a drop in pressure can cause the synchronizer to physically disengage

4. 4

   Measure the resistance of the Synchro R1 Solenoid to ensure it is within OEM specifications and not shorting out under load

1. 1

   Access the Transmission Valve Block

   Safely park the machine, relieve hydraulic pressure, and locate the transmission control valve block where the synchronizer solenoids are housed.

2. 2

   Inspect and Disconnect

   Locate the Synchro R1 Solenoid and disconnect its 2-way AMP Superseal 1.5 connector (X-644).

3. 3

   Inspect the Sensor

   Locate the Synchro F2-R1 Sensor and disconnect its 3-way Bosch BDK 2.8 connector (X-533).

4. 4

   Replace Faulty Components

   If the solenoid is mechanically sticking or electrically failing, remove the retaining hardware and replace the Synchro R1 Solenoid. If the sensor is providing erratic readings, replace the Synchro F2-R1 Sensor.

5. 5

   Repair Harness (If Applicable)

   If the fault is traced to the wiring, repair the chassis wire harness using the appropriate replacement terminals.

6. 6

   Calibrate

   After replacing transmission solenoids or sensors, perform a transmission calibration procedure using the Case IH electronic service tool to teach the TCU the new engagement characteristics.