Case IH 2579 – Transmission Control Module (UCM / Transmission ECM): Wheel speed (transmission output speed) sensor #2 - critical air gap

The distance (air gap) between the transmission output speed sensor #2 and the internal tone ring/gear it monitors is too large, or the sensor is loose, damaged, or improperly installed, causing the transmission controller to receive an erratic, intermittent, or missing signal.

• Optum
• Case IH Puma Series
• Case IH Magnum Series
• Case IH Maxxum Series

1. 1

   Check for other error codes first, as they may be causing a cascading electrical fault

2. 2

   Inspect the wiring harness and connector (X-524 or X555) to ensure it is fully seated, undamaged, and pins are in the correct position

3. 3

   Inspect the sensor mounting for a loose retaining bolt, physical damage, or incorrect installation

4. 4

   Verify the sensor is seated flush against the transmission housing to ensure the correct air gap

1. 1

   Preparation

   Park the tractor on a level surface, turn off the engine, and ensure all hydraulic pressure is relieved.

2. 2

   Locate the Sensor

   Locate transmission output speed sensor #2 on the main transmission housing.

3. 3

   Removal

   Disconnect the electrical wire harness plug from the sensor. Remove the retaining bolt holding the sensor in place and carefully pull the sensor out of the housing.

4. 4

   Inspection

   Inspect the tip of the old sensor for heavy metal shavings (which can distort the magnetic signal) or physical strike damage. If the sensor tip is physically sheared off, there is likely a mechanical fault within the transmission.

5. 5

   Installation

   Lubricate the O-ring on the new sensor (e.g., 1.4mm ID seal). Insert the new sensor into the housing, ensuring it seats completely flush to establish the correct factory air gap. Install and tighten the retaining bolt.

6. 6

   Reconnection

   Reconnect the keyed wire harness plug.

7. 7

   Clear Codes

   Turn the key switch ON. Access the 'H' menu (Diagnostic Menu) on the dot matrix display using the special diagnostic tool or armrest navigation keys. Locate the Transmission controller, navigate to the error code reduction (ECR) mode, and clear the stored fault codes from the EEPROM.

8. 8

   Test

   Test the tractor for normal operation to ensure the code does not return.