Case IH 2656 – ZTC: Reverse direction clutch KR is shorted to ground

The transmission controller has detected a short circuit to ground on the electrical circuit that controls the proportional valve/solenoid for the KR (Reverse) clutch. This prevents the transmission from engaging the reverse clutch, causing the controller to shift the transmission into Neutral and enter a limp home mode.

• Steiger T4B
• Puma
• Maxxum
• Optum
• CVX/CVT series
• 621 series
• 721 series

1. 1

   Visually inspect the wiring harness running from the ZF Transmission Controller (TCU) to the transmission control valve block for chafed insulation, pinched wires against the transmission housing, or melted wire loom.

2. 2

   Disconnect the harness at the transmission valve block and inspect the pins for corrosion, water intrusion, or bent terminals.

3. 3

   Using a multimeter, measure the resistance of the KR clutch solenoid coil at the valve block. Check for continuity between the solenoid power pin and the transmission case (ground). If there is continuity, the solenoid is internally shorted.

4. 4

   Perform a harness isolation test: with the solenoid disconnected, turn the key ON and check active fault codes. If the code changes to 'Open Circuit', the solenoid is faulty. If it remains 'Short to Ground', the wiring harness is shorted to the chassis.

1. 1

   Prepare machine

   Park the machine on a level surface, engage the parking brake, turn off the engine, and disconnect the battery ground cable.

2. 2

   Clean valve block

   Clean the exterior of the transmission valve block (usually located on the side of the transmission housing) to prevent dirt from entering the hydraulic system.

3. 3

   Disconnect solenoid

   Disconnect the electrical connector from the KR (Reverse) clutch proportional solenoid.

4. 4

   Remove retaining hardware

   Remove the retaining bolt or snap-ring securing the solenoid to the transmission valve block.

5. 5

   Remove faulty solenoid

   Carefully pull the faulty solenoid out of the valve block. Have a shop towel ready, as a small amount of transmission fluid will leak out.

6. 6

   Lubricate O-rings

   Lubricate the O-rings on the new ZF proportional solenoid with clean transmission fluid.

7. 7

   Install new solenoid

   Insert the new solenoid into the valve block bore, ensuring it seats fully without pinching the O-rings.

8. 8

   Secure solenoid

   Reinstall the retaining bolt/clip and torque to the manufacturer's specification.

9. 9

   Reconnect electrical and battery

   Reconnect the electrical connector and the battery ground cable.

10. 10

    Clear codes and test

    Connect the Case IH Electronic Service Tool (EST) to clear the stored fault codes, then start the machine and test reverse engagement to verify the repair.