Case IH 2545 – UCM (User Control Module) or Transmission ECM: Wheel speed (transmission output speed) sensor - critical air gap

The physical distance (air gap) between the transmission output speed sensor and the internal reluctor ring/gear has exceeded the acceptable tolerance. This results in an erratic, intermittent, or completely lost speed signal.

• Optum
• Puma 165
• Puma 180
• Puma 195
• Puma 210
• Puma 225 CVX
• Magnum MX210
• Magnum MX230
• Magnum MX255
• Magnum MX285

1. 1

   Check if the tractor battery has been connected to an external power supply (like a jump starter or charger). Disconnect it and test the system for normal operation, as voltage irregularities can trigger false sensor codes.

2. 2

   Check for a faulty connector or damaged wiring harness leading to the transmission output speed sensor.

3. 3

   Test the transmission output speed sensor for internal electrical faults.

4. 4

   Check for a mechanical fault within the transmission (such as excessive shaft end-play or a loose tone ring) that could be physically pushing the sensor away or widening the air gap.

1. 1

   Locate the Sensor

   Locate the transmission output speed sensor on the transmission housing.

2. 2

   Inspect the Air Gap / Mounting

   Remove the sensor and inspect the mounting bore. Ensure no dirt, debris, or old O-rings are preventing the sensor from seating fully against the housing, which would artificially widen the air gap.

3. 3

   Check the Tone Ring

   Look through the sensor bore to inspect the internal gear/tone ring. Verify it is tight and undamaged.

4. 4

   Replace the Sensor and Seal

   If the sensor is faulty or the tip is damaged (indicating it struck the internal gear), install a new sensor. Always use a new O-ring/seal when installing the sensor to prevent fluid leaks.

5. 5

   Clear Codes

   Once the mechanical or electrical cause has been rectified, use a diagnostic tool to clear the error code from the UCM and test drive the tractor to verify normal operation.