Case IH 2739 (517971.06) - DEC – Transmission Control Module (TCU) / Universal Control Module (UCM): R1 solenoid - LSD short to HSD

A severe electrical circuit fault where the Low Side Driver (LSD) is shorted directly to the High Side Driver (HSD) on the circuit controlling the R1 (Reverse 1) synchronizer solenoid. This bypasses the solenoid load entirely, creating a direct short circuit, causing the controller to disable the circuit and preventing the transmission from engaging the R1 synchronizer.

• VESTRUM CVX
• Case IH Magnum Series (210, 220, 245, 255, 285, 340)
• Case IH Puma Series (165, 180, 195, 210, 225)
• Case IH Steiger Series

1. 1

   Visually inspect the R1 synchronizer solenoid connector, intermediate wire harness connectors, and UCM (Transmission Controller) connectors for melted wires, rubbed-through insulation, or bent pins.

2. 2

   Perform a solenoid resistance test: Disconnect the R1 solenoid connector and measure resistance across the two terminals on the solenoid (should be approximately 10 Ohms). A reading of 0 Ohms indicates an internal short.

3. 3

   Perform a harness short test: With the solenoid and UCM disconnected, check for continuity between the High Side wire and the Low Side wire in the harness. Continuity indicates the wiring harness has melted or rubbed together.

4. 4

   Perform a ground short test: Check for continuity between both the HSD and LSD wires to the chassis ground. Neither should be grounded when unplugged from the UCM.

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 (typically on the side or top of the transmission housing, depending on the tractor model). Identify the R1 synchronizer solenoid.

3. 3

   Disconnect

   Unplug the 2-pin electrical connector from the R1 solenoid.

4. 4

   Harness Repair (If Applicable)

   If the diagnostic checks revealed a short in the wiring, trace the harness back to the UCM. Cut out the melted/shorted section of the wire and splice in new wiring using weather-sealed heat-shrink butt connectors. Replace the 2-pin connector pigtail if the short occurred at the plug.

5. 5

   Solenoid Replacement (If Applicable)

   If the solenoid failed the resistance test, clean the area around the valve block to prevent dirt ingress. Remove the retaining bolt or snap-ring holding the R1 solenoid in place. Pull the solenoid cartridge out of the valve body.

6. 6

   Installation

   Lubricate the O-rings on the new solenoid with clean transmission fluid. Insert it into the valve block and secure it with the retaining bolt/clip.

7. 7

   Reassembly

   Plug the electrical connector back into the solenoid. Reconnect the battery.

8. 8

   Calibration & Clearing

   Connect the dealer diagnostic tool (EST) or use the tractor's display monitor to clear the stored 2739 / 517971.06 fault code. Run a transmission calibration procedure to ensure the UCM relearns the engagement points for the new R1 synchronizer solenoid.