Case IH 2119 (6156.03) - DEC – DEC: Synchro 5 Solenoid Short to 12V

The Low Side Driver (LSD) circuit for the Synchro 5 Solenoid is shorted to high voltage (12V). The controller detects unexpected battery voltage on the ground circuit, preventing the module from grounding the circuit to activate the solenoid, thereby disabling the engagement of the 5th synchronizer in the transmission.

• MAXXUM T4E
• Magnum
• Steiger
• Versatile
• T-series

1. 1

   Visually inspect the transmission wiring harness for chafing, melted insulation, or pinch points, particularly where the harness routes along the transmission housing to the valve body solenoids.

2. 2

   Disconnect the Synchro 5 Solenoid connector. With the key ON (engine OFF), use a multimeter to probe the Low Side Driver (ground) pin on the harness side. If it reads 12V, there is a short to power in the wiring harness between the solenoid and the DEC.

3. 3

   Disconnect the harness from the DEC. Check for continuity between the LSD circuit wire and a 12V power source.

4. 4

   Measure the resistance across the pins of the Synchro 5 Solenoid itself. Check for continuity between the solenoid pins and the solenoid casing to ensure the solenoid is not internally shorted to ground/power.

5. 5

   Inspect the DEC and solenoid connectors for water intrusion, corrosion, or bent pins, which can bridge circuits and cause a short to high voltage.

1. 1

   Prepare the machine

   Park the tractor on a level surface, engage the parking brake, and turn off the engine.

2. 2

   Disconnect battery

   Disconnect the negative battery cable to prevent electrical damage or accidental shorting during the repair.

3. 3

   Locate solenoid

   Locate the Synchro 5 Solenoid on the transmission valve body (refer to the specific model's transmission housing diagram, such as the 1402 Powershift housing).

4. 4

   Repair or replace harness

   If the harness is shorted: Locate the chafed or damaged section of the wiring harness identified during diagnostics. Repair the wire using OEM-approved heat-shrink butt connectors, or replace the affected transmission harness section if the damage is extensive.

5. 5

   Remove solenoid retaining hardware

   If the solenoid is internally shorted: Remove the retaining bolt or snap ring securing the Synchro 5 Solenoid to the valve body.

6. 6

   Remove solenoid

   Carefully pull the solenoid straight out.

7. 7

   Install new solenoid

   Lubricate the O-rings on the new replacement solenoid with clean transmission fluid and press it into the valve body bore. Secure it with the retaining bolt/clip.

8. 8

   Reconnect electrical connector

   Reconnect the electrical connector, ensuring the weather-pack seal is intact and the locking tab clicks.

9. 9

   Reconnect battery

   Reconnect the battery.

10. 10

    Clear codes and test drive

    Clear the fault codes using the tractor's instrument cluster interface (INC/DEC keys) or the EST diagnostic software. Test drive the machine to verify the 5th synchronizer engages properly without throwing a code.