Case IH 2220 – ZDC: Transmission Output Speed Overspeed

The transmission output speed sensor is registering an RPM value that exceeds the maximum allowable limit for the current operating state, or the output speed does not match the commanded output speed. This discrepancy is typically caused by a faulty output speed sensor, a misadjusted sensor, erratic input speed readings, or internal transmission slippage (such as a slipping clutch pack).

• Steiger T4B
• Magnum CVT / Rowtrac Series (e.g., 180, 250, 280, 310, 340, 380)
• Steiger CVT Series (e.g., 420)
• Puma CVT / CVX Series
• Maxxum CVT Series

1. 1

   Service Tool Verification: Connect the electronic service tool to the tractor. Navigate to the monitor screen, select the parameter selections icon, and monitor the 'inst trans output speed' (Transmission Output Speed in RPM) while driving. Look for erratic, intermittent, or spiking readings that do not match the actual ground speed.

2. 2

   Wiring and Connector Inspection: Inspect the wiring harness leading to the transmission output speed sensor. Look for short circuits, chafed wires, or poor pin connections, which are common causes of erratic speed signals.

3. 3

   Sensor Adjustment: Verify that the transmission output speed sensor is properly mounted and adjusted to the correct depth/air gap.

4. 4

   Mechanical Slippage Check: If the sensor reads accurately but the code persists under load, evaluate the transmission for mechanical clutch pack slipping.

1. 1

   Power Down

   Park the machine on a level surface, engage the parking brake, and turn off the key switch. Disconnect the battery if repairing wiring.

2. 2

   Locate the Sensor

   Locate the Transmission Output Speed Sensor on the CVT housing. (Note: Some CVT models utilize two output speed sensors for redundancy; check both if applicable).

3. 3

   Inspect the Harness

   Disconnect the 2-pin connector at the sensor. Clean the contacts with electrical contact cleaner and verify there is no moisture or corrosion.

4. 4

   Replace the Sensor

   If the wiring is intact but the sensor output was erratic on the service tool, remove the retaining bolt holding the speed sensor and pull the sensor from the housing.

5. 5

   Install the New Sensor

   Lubricate the O-ring on the new sensor with clean transmission fluid. Insert it into the housing and torque the retaining bolt to OEM specifications.

6. 6

   Recalibrate

   Reconnect the battery and harness. Use the Case IH service tool to clear the ZDC fault codes and perform a transmission calibration if required by the service manual.