Case IH 2629 – ZTC: Hydrostatic Unit Speed Sensor 2 (N_Hyd2) Circuit Open or Shorted to Power

The controller has detected that the electrical circuit for the Hydrostatic Unit Speed Sensor 2 (N_Hyd2) is either open (a broken wire or disconnected plug) or shorted to power (the signal wire is improperly receiving voltage, likely from chafing against a live wire).

• Steiger T4B
• Puma CVX
• Optum CVX
• Magnum CVX
• Steiger CVT

1. 1

   Visually inspect the N_Hyd2 sensor wiring harness on the transmission housing for obvious signs of chafing, melting, or rodent damage.

2. 2

   Unplug the sensor and check the pins inside the connector for corrosion, moisture ingress, or pushed-out pins.

3. 3

   Test for an open circuit by using a multimeter to check for continuity on the signal and ground wires between the sensor connector and the ZTC module harness.

4. 4

   Test for a short to power by probing the sensor's signal wire with the key ON (engine OFF) to ensure it is not receiving 12V power from a compromised neighboring wire.

5. 5

   If the wiring tests perfectly, test the sensor itself, as the internal coil or circuitry of the Hall-effect/inductive N_Hyd2 sensor has likely failed open.

1. 1

   Preparation

   Park the tractor on a level surface, engage the parking brake, turn off the engine, and disconnect the negative battery terminal to prevent electrical spikes.

2. 2

   Clean the Area

   Thoroughly clean the transmission housing around the N_Hyd2 sensor to prevent dirt from falling into the hydrostatic unit during removal.

3. 3

   Remove the Sensor

   Disconnect the electrical pigtail. Remove the retaining bolt(s) holding the sensor to the transmission housing. Carefully pull the sensor straight out.

4. 4

   Install the New Sensor

   Coat the O-ring of the new speed sensor with clean Case IH Akcela transmission/hydraulic fluid to prevent tearing. Insert the sensor into the port and seat it fully.

5. 5

   Secure and Reconnect

   Install and tighten the retaining bolt to OEM torque specs. Reconnect the electrical harness, ensuring the locking tab clicks into place.

6. 6

   Clear and Calibrate

   Reconnect the battery. Use a diagnostic tool to clear the ZTC fault codes. Start the tractor and perform a test drive. Note: Depending on the specific tractor model, a hydrostatic unit calibration routine may need to be run via the tractor's display monitor after replacing a speed sensor.