Case IH 2738 (517971.03) - DEC – Transmission Control Unit (TCU) or Vehicle Control Module (UCM): R1 Solenoid - LSD short to high voltage

The control module is detecting that the voltage on the low side driver circuit is unexpectedly high during the driver's 'off' state. This indicates that the circuit has a short to power (e.g., a 12V source) somewhere in the wiring harness, or there is an internal short within the solenoid or the controller itself.

• VESTRUM CVX
• Case IH Magnum Series: 180, 200, 210, 220, 240, 250, 275, 280, 310, 340, 380 (Tier 4B CVT and PST models)
• Case IH Steiger Series: 350, 370, 420, 470, 500, 540, 580, 620
• Case IH Puma Series: 165, 170, 180, 185, 195, 200, 210, 215, 225, 230 (CVX and standard powershift)

1. 1

   Inspect the transmission chassis wiring harness for physical damage, chafing, or melted insulation that could cause the solenoid's ground wire to short against a 12V power wire.

2. 2

   Disconnect the 2-pin electrical connector at the R1 solenoid and check for water ingress, corrosion, or bent pins.

3. 3

   With the key in the OFF position, use a multimeter to measure the resistance across terminal 1 and terminal 2 of the R1 solenoid (should be 8 to 11 Ohms).

4. 4

   With the solenoid disconnected and the ignition ON, check the harness side of the Low Side Driver pin for unexpected voltage to confirm if the short to power is in the wiring harness.

1. 1

   Preparation

   Turn off the engine, apply the parking brake, and ensure all hydraulic and transmission pressure is relieved before removing any valves or covers.

2. 2

   Access the Valve Block

   Locate the R1 transmission synchronizer/clutch solenoid on the transmission control valve block.

3. 3

   Disconnect

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

4. 4

   Replace Solenoid (if failed)

   If the resistance test (8-11 Ohms) failed, remove the retaining fastener for the R1 solenoid and pull the cartridge valve out. Lubricate the O-rings on the new solenoid with clean transmission fluid and install it.

5. 5

   Repair Harness (if failed)

   If the solenoid tests good but the harness has a short to power, trace the chassis harness back to the UCM/TCU and repair the shorted wires. Replace the 2-pin pigtail connector if it is melted or heavily corroded.

6. 6

   Clear Codes

   Once the physical repair is complete, clear the stored fault codes. On many Case IH displays, this can be done via the H8 menu (which clears EEPROM fault codes and calibration values).

7. 7

   Recalibrate Transmission

   Because transmission components were replaced or codes were cleared, perform a transmission calibration. Ensure the transmission oil temperature is between 60°C and 105°C (140°F+) before running the calibration.