New Holland TRANS 77 – Transmission Controller (TCU): No signal from wheel speed sensor

The transmission controller detects that the signal from the output shaft wheel speed sensor is either too weak or completely non-existent.

• TG210
• TG230
• TG255
• TG285
• TJ430
• T8000 Series
• Magnum
• STX Steiger series
• STX 325

1. 1

   Check the instrumentation display to see if wheel speed is registering (if not equipped with a radar gun).

2. 2

   If a ground speed radar is installed, disconnect it temporarily, drive the tractor, and observe the display to see if the wheel speed registers.

3. 3

   Thoroughly inspect the wiring harness between the output shaft wheel speed sensor and the transmission controller for open circuits, shorts, or corrosion.

1. 1

   Locate the Sensor

   Find the output shaft wheel speed sensor located on the transmission housing.

2. 2

   Inspect Connectors

   Disconnect the sensor's electrical connector. Check for dust, moisture, or corrosion, which are common causes of electrical connection failures in agricultural equipment.

3. 3

   Test Continuity

   Using a multimeter, test the continuity of the wiring harness from the sensor connector back to the transmission controller pins. Repair any damaged wires or replace faulty connector pins.

4. 4

   Replace the Sensor

   If the wiring harness tests good and the connection is clean, the sensor itself has failed internally. Remove the faulty output shaft wheel speed sensor and install the replacement part.

5. 5

   Verify Repair

   Reconnect the sensor, clear the fault codes using an Electronic Service Tool or diagnostic code reader, and test drive the tractor to ensure the wheel speed displays correctly and the TRANS 77 code does not return.