Case IH 31 – Transmission ECM: Reverse (Shuttle) Synchronizer Solenoid Coil Short Circuit

The Reverse (Shuttle) Synchronizer Solenoid experiences a short circuit while the tractor is being driven in reverse or while in neutral. The Transmission Status Lamp (Hi and Lo lamps) will flash in an alternating manner.

• JXC
• MXU series
• JX series
• Farmall series
• TN series

1. 1

   Check wiring harness for a short circuit between ECM connector 1, pin 17 and ECM connector 1, pin 3 wires, or directly across the two coil terminals.

2. 2

   Test the Reverse (Shuttle) Synchronizer Solenoid Coil for internal shorts.

3. 3

   Use the Electronic Service Tool (EST) H5 menu to check circuit status/continuity, or H9 menu (channel 13) to monitor live circuit data.

4. 4

   If wiring and solenoid coil test within normal resistance specifications, verify if the ECM itself is faulty.

1. 1

   Access the Transmission Solenoid Valve Block

   Locate the reverse (shuttle) synchronizer solenoid on the transmission housing.

2. 2

   Inspect and Repair Wiring

   Disconnect the harness from the solenoid and the ECM. Use a multimeter to check for continuity and shorts between ECM connector 1 (Pins 17 and 3). Repair any chafed or melted wires.

3. 3

   Replace the Solenoid

   If the wiring harness is intact but the solenoid coil is shorted, remove the retaining nut/bolt on the solenoid coil and slide the faulty coil off the valve stem. Install the new Reverse Synchronizer Solenoid Coil.

4. 4

   Replace the ECM

   If both the wiring and solenoid are perfectly functional, replace the Transmission ECM.

5. 5

   Recalibrate

   After replacing the reverse synchronizer solenoid or ECM, the transmission must be recalibrated using the dealer service tool to ensure proper shuttle engagement.