Case IH 735-01 - DEC – Transmission Control Unit (TCU) or Transmission ECU: Transmission Range Clutch C2 Solenoid electrical circuit fault, voltage low

The control module has detected that the voltage in the electrical circuit for the Transmission C2 clutch solenoid is below the normal operating range. This typically indicates a short to ground, an open circuit, or a failed solenoid coil.

• MAGNUM AFS Connect
• Farmlift 632
• Farmlift 635
• Farmlift 735
• Farmlift 742
• Farmlift 935
• Steiger
• Magnum
• Maxxum
• MXU110
• MXU135

1. 1

   Inspect the wiring harness between the Transmission ECU and the C2 clutch solenoid for chafing, melted insulation, or damage

2. 2

   Disconnect the C2 solenoid and the ECU harness to check connectors for bent pins, corrosion, or moisture

3. 3

   Measure resistance across the pins of the C2 clutch solenoid coil (0 ohms indicates a shorted coil, infinite indicates an open/failed coil)

4. 4

   Check for shorts to ground by measuring resistance from the solenoid power wire to the chassis ground (a reading of less than 5,000 ohms indicates a short in the harness)

5. 5

   Verify that the machine's battery and charging system are delivering proper voltage, as low system voltage can trigger false solenoid codes

1. 1

   Preparation

   Park the machine on a firm, level surface. Apply the parking brake, turn off the engine, and turn the battery disconnect switch to the OFF position.

2. 2

   Locate the Solenoid

   Locate the transmission control valve block (usually mounted on the side or top of the transmission housing). Identify the C2 clutch solenoid.

3. 3

   Disconnect Wiring

   Carefully unplug the electrical connector from the C2 solenoid.

4. 4

   Remove the Solenoid

   Remove the retaining bolt or snap ring holding the solenoid valve in the valve block. Pull the solenoid straight out. Note: Have a catch pan ready, as a small amount of transmission fluid will leak.

5. 5

   Install the New Solenoid

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

6. 6

   Reconnect

   Plug the electrical connector back into the solenoid, ensuring the locking tab clicks into place.

7. 7

   Clear Codes and Calibrate

   Turn the battery disconnect switch ON. Connect a diagnostic tool (like the Case IH Electronic Service Tool) to clear the inactive fault codes. Depending on the tractor/telehandler model, you may need to perform a transmission clutch calibration procedure via the cab display or diagnostic tool.

8. 8

   Test

   Start the engine and test drive the machine through all gears to ensure the C2 clutch engages smoothly and the fault code does not return.