Case IH 2086 (6156.05) - DEC – Transmission Controller / DEC: Synchro 5 Solenoid - open circuit

The transmission controller constantly monitors the voltage on the solenoid circuits. If the voltage on the Synchro 5 circuit drops below the expected threshold, the controller flags an "open circuit". This means electrical continuity to the solenoid has been lost, preventing the transmission from properly engaging the 5th synchronizer range.

• MAXXUM T4E
• Puma
• Maxxum
• Magnum
• Steiger
• T6000
• T7
• T8
• TS
• TL

1. 1

   Check Power Supply: Verify that the transmission controller and the neutral latch relay are supplying power to the solenoid circuit. A blown fuse or a dropped power supply can trigger a false open circuit code.

2. 2

   Visual Wiring Inspection: Inspect the wiring harness running from the DEC/Transmission Controller to the transmission valve block. Look for rubbed-through wires, rodent damage, or pinched harnesses.

3. 3

   Connector Check: Disconnect the harness at the Synchro 5 solenoid. Check for water intrusion, pushed-out pins, or heavy corrosion.

4. 4

   Ohm Test the Solenoid: Using a multimeter, measure the resistance across the pins of the Synchro 5 solenoid coil. If the multimeter reads "OL" (infinite resistance), the internal coil is broken (open) and the solenoid must be replaced.

5. 5

   Harness Continuity Test: If the solenoid tests good, check the continuity of the wires from the solenoid connector back to the transmission controller pins to find the break in the wire.

1. 1

   Power Down

   Turn off the tractor, remove the key, and disconnect the negative battery cable to prevent electrical spikes.

2. 2

   Locate the Solenoid

   Locate the transmission control valve block (usually mounted on the side or top of the transmission housing). Identify the Synchro 5 solenoid (refer to your specific model's hydraulic schematic if the solenoids are not stamped).

3. 3

   Remove the Faulty Component

   Disconnect the electrical connector. Depending on the design, you may be able to slide just the solenoid coil off the valve stem by removing a retaining nut, or you may need to unthread the entire solenoid cartridge assembly.

4. 4

   Install the New Part

   Slide the new solenoid coil onto the valve stem and secure the retaining nut (do not overtighten, as this can crack the plastic housing), or thread the new cartridge into the valve block and torque to OEM spec.

5. 5

   Reconnect and Reassemble

   Plug the electrical connector back in, ensuring the weather seal is intact and it clicks into place.

6. 6

   Clear Codes and Test

   Reconnect the battery. Turn the key on and clear the inactive fault codes from the DEC. Start the tractor and test the transmission by shifting through the ranges (specifically the 5-8 or 13-16 ranges) to ensure the synchronizer engages smoothly and the code does not return.