Case IH 2050 (191.03) - DEC – Transmission Electronic Control Module (Transmission ECM / TCU): Wheel speed (transmission output speed) sensor – short to 12V / short to high voltage

The Transmission Output Speed (TOS) sensor monitors the rotational speed of the transmission output shaft to calculate ground/wheel speed. A 'short to high voltage' means the transmission controller is receiving a constant high voltage (such as 12V) on the sensor's signal circuit instead of the expected pulsed frequency, usually due to a wiring short or an internal sensor failure.

• MAXXUM T4E
• Case IH Puma Series (165, 180, 195, 210, 225 CVX)
• Case IH Magnum Series (Tier 4A/4B, PST, CVT, AFS Connect)
• Case IH Maxxum Series (135, 145, 150)
• Case IH Farmall Series (95U, 105U, 115U Pro EP)

1. 1

   Monitor Output Test: Connect the service tool or use the in-cab monitor screen to check 'inst ground speed - wheel' or 'inst trans output speed' for RPM/MPH data.

2. 2

   Visual Inspection: Inspect the 4-way electrical connector (X555) at the sensor for dirt, corrosion, or pushed-out pins.

3. 3

   Wiring Harness Check: Trace the wiring harness from the TOS sensor back to the Transmission ECM. Look for chafed wires shorting the signal wire directly to a 12V power source.

4. 4

   Sensor Verification: Disconnect the sensor. If the fault changes from a 'short to high voltage' to an 'open circuit' (code 2049), the wiring is likely intact and the sensor is internally shorted.

1. 1

   Preparation

   Park the tractor on a level surface, turn off the engine, remove the key, and engage the parking brake. Ensure all hydraulic and transmission pressure is relieved.

2. 2

   Locate the Sensor

   Locate the Transmission Output Speed Sensor, which is typically mounted on the rear axle housing or the transmission output housing.

3. 3

   Disconnect Wiring

   Carefully unplug the 4-way electrical connector from the sensor.

4. 4

   Clean the Area

   Thoroughly clean the area around the sensor base to prevent dirt or debris from falling into the transmission housing when the sensor is removed.

5. 5

   Remove the Sensor

   Remove the retaining bolt/nut securing the sensor. Pull the sensor straight out of the housing.

6. 6

   Install the New Sensor

   Lubricate the O-ring on the new sensor with clean transmission fluid. Insert the new sensor into the housing and secure it with the retaining hardware.

7. 7

   Reconnect and Clear Codes

   Reconnect the electrical harness. Turn the key ON, use the tractor's monitor or a service tool to clear the inactive 2050 fault code, and test drive the tractor to verify that the transmission output speed registers correctly.