Case IH 2576 (3825.04) - DEC – Transmission Controller / Transmission ECM: Wheel speed (transmission output speed) sensor #2 - short to ground or open circuit

The transmission electronic control module (ECM) has detected that the signal circuit for the #2 transmission output speed (TOS) sensor has lost electrical continuity (an open circuit) or the wiring has shorted directly to ground. When this occurs, the transmission controller loses a critical speed input, which can inhibit upshifts in high range and cause a 1-2 second delay in allowing upshifts after a clutchless takeoff.

• MAXXUM T4E
• VESTRUM CVX
• Puma
• Maxxum
• Magnum
• Steiger

1. 1

   Service Tool Verification: Connect the electronic service tool to the tractor. Navigate to the monitor screen, select 'inst trans output speed,' and monitor the sensor output in RPM while the tractor is moving to see if any signal is being generated.

2. 2

   Wiring Harness Test: Disconnect the transmission processor connectors (e.g., C100 & C101) and the transmission output speed sensor connector. Test the wiring harness for an open circuit or a short to ground between the sensor connector and the transmission controller pins.

3. 3

   Sensor Short Test: With the sensor still installed in the transmission, use a multimeter to check for a short to earth (ground) on each of the sensor's terminal pins.

4. 4

   Sensor Resistance Test: Check the internal resistance of the sensor across its terminals. An open reading (infinite resistance) indicates a broken internal coil, meaning the sensor has failed.

5. 5

   Sensor Logic Check: The transmission ECM compares the signals of TOS sensor #1 and TOS sensor #2. Verify that the two sensors have not been accidentally swapped or connected backwards during previous maintenance.

1. 1

   Turn off the tractor, apply the parking brake, and ensure the key switch is in the OFF position.

   Turn off the tractor, apply the parking brake, and ensure the key switch is in the OFF position.

2. 2

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

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

3. 3

   Disconnect the electrical connector from the transmission output speed sensor.

   Disconnect the electrical connector from the transmission output speed sensor.

4. 4

   Inspect the wiring harness connector for pushed-out pins, moisture, or corrosion. If the connector is damaged, splice in a replacement connector pigtail.

   Inspect the wiring harness connector for pushed-out pins, moisture, or corrosion. If the connector is damaged, splice in a replacement connector pigtail.

5. 5

   If the wiring tests OK but the sensor failed the resistance/short diagnostics, remove the retaining hardware and extract the speed sensor from the transmission housing.

   If the wiring tests OK but the sensor failed the resistance/short diagnostics, remove the retaining hardware and extract the speed sensor from the transmission housing.

6. 6

   Clean the mounting port on the transmission housing. Lubricate the O-ring/seal on the new sensor with clean transmission fluid.

   Clean the mounting port on the transmission housing. Lubricate the O-ring/seal on the new sensor with clean transmission fluid.

7. 7

   Install the new transmission output speed sensor and tighten the retaining hardware to OEM torque specs.

   Install the new transmission output speed sensor and tighten the retaining hardware to OEM torque specs.

8. 8

   Reconnect the electrical connector securely.

   Reconnect the electrical connector securely.

9. 9

   Turn the key ON and use the tractor's diagnostic H-Menu or an electronic service tool to clear the stored fault codes. Test drive the tractor to verify that transmission shifting returns to normal and the code does not return.

   Turn the key ON and use the tractor's diagnostic H-Menu or an electronic service tool to clear the stored fault codes. Test drive the tractor to verify that transmission shifting returns to normal and the code does not return.