Case IH 2128 (5960.03) - DEC – Transmission Control Module (TCM / TCU): Odd Shaft Speed - short to high voltage or open circuit

The fault indicates an electrical failure in the circuit for the Odd Shaft Speed Sensor. A 'short to high voltage or open circuit' means the control module is not receiving a valid signal because the wiring is physically broken/disconnected (open circuit) or a wire has chafed and is touching a power source (short to high voltage). Without this signal, the transmission cannot properly time shifts for the odd gears.

• MAXXUM T4E
• Maxxum
• Puma
• Magnum

1. 1

   Visually inspect the wiring harness leading to the transmission speed sensors for pinched wires, rodent damage, or chafing against the transmission housing.

2. 2

   Disconnect the odd shaft speed sensor and check for water intrusion, bent pins, or corrosion inside the connector.

3. 3

   Connect a diagnostic scan tool and monitor the 'Odd Shaft Speed' live data parameter (a reading of 0 RPM while the engine is running and clutch is engaged indicates a missing signal).

4. 4

   Use a multimeter to check the sensor's supply voltage and ground at the connector, and perform a continuity test on the signal wire between the sensor and TCM to confirm if the wire is broken or shorted.

1. 1

   Disconnect Power

   Disconnect the machine's battery to prevent electrical spikes.

2. 2

   Locate the Sensor

   Locate the odd shaft speed sensor on the exterior of the transmission housing.

3. 3

   Repair Wiring

   If the diagnostic circuit test revealed a broken wire or a short to power in the harness, splice and repair the damaged section of the wiring harness using weather-sealed connectors.

4. 4

   Remove Sensor

   If the harness tests perfectly, the sensor has failed internally. Remove the retaining bolt holding the sensor.

5. 5

   Extract Sensor

   Carefully pull the sensor straight out of the housing. Caution: The tone wheel blades inside the transmission that the sensor reads can be fragile. Do not pry aggressively or drop debris into the transmission port.

6. 6

   Install New Sensor

   Lubricate the O-ring on the new sensor with clean transmission fluid. Insert the sensor, install the retaining bolt, and torque to OEM specifications.

7. 7

   Clear Codes and Test

   Reconnect the battery, connect a diagnostic tool, and clear the TCM fault codes. Test drive the tractor to ensure odd-numbered gears engage smoothly.