Case IH 2577 (3825.03) - DEC – Transmission Controller (Transmission ECM / TCU): Wheel Speed (Transmission Output Speed) Sensor #2 - Short to 12V

The transmission electronic control module (ECM) has detected that the signal circuit for the Transmission Output Speed Sensor 2 is shorted to a high voltage source (12 Volts).

• MAXXUM T4E
• Case IH Puma Series (165, 180, 195, 210, 225 CVX)
• Case IH Magnum Series
• Case IH Maxxum Series
• Case IH Steiger Series

1. 1

   Monitor Screen Verification: Connect the service tool or use the tractor's monitor screen. Select 'inst trans output speed' to display the sensor output in RPM. Check if the reading is erratic or stuck due to the short.

2. 2

   Wiring Harness Inspection: Inspect the wiring harness leading to Transmission Output Speed Sensor 2 for melted insulation, corrosion, or pinch points, looking for a chafed wire rubbing against a power wire.

3. 3

   Pin Connection Check: Turn the key switch to the OFF position. Disconnect the transmission ECM harness and verify that the sensor is correctly pinned (e.g., checking continuity on the specific J1 pins for Sensor 2).

4. 4

   Sensor Swap Test: Ensure the connectors for Sensor 1 and Sensor 2 have not been accidentally swapped during previous maintenance.

1. 1

   Safety First

   Turn the key start switch to the OFF position and disconnect the battery to prevent electrical spikes. Ensure all hydraulic and pneumatic pressure is relieved.

2. 2

   Locate the Sensor

   Locate Transmission Output Speed Sensor 2 on the transmission/rear axle housing.

3. 3

   Disconnect and Isolate

   Disconnect the electrical plug from the sensor. Use a multimeter to test the harness-side connector for voltage on the signal wire with the key ON. If 12V is present on the signal return wire, the harness must be repaired or replaced.

4. 4

   Remove the Sensor

   If the harness tests fine, the sensor itself has an internal short. Clean the area around the sensor thoroughly to prevent dirt from entering the transmission housing. Unbolt and remove the faulty sensor.

5. 5

   Install the New Sensor

   Lubricate the O-ring/seal on the new sensor. Install the sensor into the housing and tighten the retaining bolt to OEM torque specs.

6. 6

   Reconnect

   Plug the electrical connector back into the sensor. Reconnect the battery.

7. 7

   Clear Codes and Test

   Turn the key to the ON position. Access the tractor's 'H-Menu' (or use the service tool) and perform an 'HC' operation to erase all stored error codes. Operate the machine at or above third gear for at least 30 seconds to verify the code does not return.