Case IH 2667 (6155.11) - DEC – Transmission Control Unit (TCU) or Vehicle Control Unit (VCU): Synchro 4 Solenoid - Generic Error

Malfunction in the circuit or mechanical operation of the transmission's 4th synchronizer solenoid.

• MAXXUM T4E
• Case IH Maxxum
• Case IH Puma
• Case IH Magnum

1. 1

   Inspect the transmission wiring harness leading to the transmission valve block for chafing, pinched wires, or heat damage.

2. 2

   Disconnect the Synchro 4 solenoid plug and check for water ingress, dirt, or corroded pins.

3. 3

   Using a multimeter, test the wiring harness between the TCU and the solenoid connector for continuity and ensure there is no short to ground or 12V power.

4. 4

   Measure the resistance (Ohms) across the pins of the Synchro 4 solenoid coil to check for internal failure (infinite resistance/open or zero resistance/shorted).

1. 1

   Preparation

   Park the tractor on a level surface, engage the parking brake, turn off the engine, and relieve any residual hydraulic pressure.

2. 2

   Locate the Solenoid

   Locate the transmission control valve block (usually on the side or top of the transmission housing) and identify the Synchro 4 solenoid.

3. 3

   Clean the Area

   Thoroughly clean the area around the valve block with brake cleaner to prevent dirt from entering the transmission hydraulics.

4. 4

   Removal

   Disconnect the electrical harness. Remove the retaining bolts or snap ring securing the solenoid to the valve block. Carefully pull the solenoid out.

5. 5

   Inspection

   Inspect the valve spool and bore for metal debris or scoring, which could indicate deeper transmission wear.

6. 6

   Installation

   Lubricate the O-rings on the new Synchro 4 solenoid with clean transmission fluid. Insert the new solenoid into the valve block and torque the retaining bolts to OEM specifications.

7. 7

   Reconnection

   Reconnect the electrical harness, ensuring the locking tab clicks into place.

8. 8

   Calibration

   Connect a diagnostic tool to clear the fault codes. You will likely need to perform a transmission/clutch calibration procedure to teach the TCU the engagement points of the new solenoid.

9. 9

   Test Drive

   Operate the tractor through all gears to verify smooth shifting and ensure the fault code does not return.