Case IH 2522 – UCM (Unit Control Module) or CCU (Central Control Unit): R1 solenoid - open circuit or short circuit to ground

This code indicates an electrical fault in the transmission's R1 (Reverse 1) synchronizer solenoid circuit. The system has detected that the circuit is either broken (open circuit) or the wiring has chafed and is touching the chassis (short circuit to ground), preventing the controller from operating the R1 synchronizer.

• Optum
• Case IH Magnum Series (210, 220, 230, 245, 255, 275, 285, 305)
• Case IH Puma Series (165, 180, 195, 210, 225 CVX)
• Case IH MX / TG Series

1. 1

   Inspect the R1 solenoid connector for dirt, corrosion, or pushed-back pins

2. 2

   Test solenoid resistance by disconnecting the R1 synchronizer solenoid and measuring resistance between terminal 1 and 2 (should be approximately 10 Ohms, acceptable range 8 to 11 Ohms)

3. 3

   Test the wiring harness for a short to ground or power by disconnecting the UCM connector, turning ignition ON, and measuring voltage between the R1 signal pin and ground

4. 4

   Test the wiring harness for an open circuit by checking for continuity from the UCM connector pin to the solenoid connector pin

1. 1

   Locate the Solenoid

   Park the machine safely, turn off the ignition, and locate the R1 synchronizer solenoid on the transmission control valve block.

2. 2

   Disconnect and Test

   Unplug the 2-pin electrical connector from the solenoid. Use a multimeter to perform the resistance test (10 Ohms).

3. 3

   Replace Solenoid (If Faulty)

   If the resistance is out of spec (e.g., infinite resistance indicating an internal open, or 0 Ohms indicating an internal short), unbolt the faulty R1 solenoid, replace it with a new unit, and torque to OEM specifications.

4. 4

   Repair Wiring (If Solenoid is Good)

   If the solenoid tests fine, the fault lies in the wiring. Trace the harness back to the UCM. Repair any chafed wires causing a short to ground, or splice/replace broken wires causing an open circuit.

5. 5

   Replace Connector (If Damaged)

   If the locking tab is broken or pins are corroded, splice in a new 2-pin pigtail connector.

6. 6

   Clear Codes

   Reconnect all components. Turn the key ON and use the tractor's diagnostic menu (often the "HC" menu on the display) or an electronic service tool to clear the stored error codes.

7. 7

   Test Operation

   Start the tractor and shift through the ranges to ensure the R1 synchronizer engages smoothly and the code does not return.