Deutz-Fahr T12 – TCU: Trans Oil Temp Sensor Disconnected/Short

The Transmission Control Unit (TCU) has detected that the transmission oil temperature sensor is disconnected or shorting to battery positive (12V). This prevents the control unit from accurately monitoring the transmission fluid temperature.

• Agroplus 310, 320, 410, and 420 Profiline series tractors
• Agrofarm 85
• Agrofarm 100
• Agrofarm 410
• Agrofarm 420
• Agrofarm 430
• Agrotron MK3 (106, 110, 115, 120, 135, 150, 165)
• Agrotron M
• Agrotron New
• Agrotron K (K90, K100, K110, K120, K410, K420, K430, K610)
• Agrotron TTV
• Agrotron Profiline
• Agrotron X
• Agrotron Series 6
• Agrotron Series 7
• Agrotron Series 9
• SAME Iron
• SAME Diamond
• SAME Fortis
• SAME Spark
• SAME R6
• Lamborghini Iron
• Lamborghini Diamond
• Lamborghini Fortis
• Lamborghini Spark
• Lamborghini R6

1. 1

   Unplug the transmission oil temperature sensor and measure the resistance between the two pins on the sensor-sided connector. The resistance value should be approximately 1 kilo-ohm ± 100 ohms (or 2 kilo-ohms for production dates before 06/2007).

2. 2

   If the sensor tests within specification, check the wiring harness between the sensor and the TCU for a broken wire (disconnected state) or a short circuit to a 12V power source.

3. 3

   Check the sensor and harness connectors for corrosion, pushed-out pins, or physical damage.

1. 1

2. 2

   Disconnect battery

   Disconnect the tractor's battery to prevent electrical shorts during the repair.

3. 3

   Locate sensor

   Locate the transmission oil temperature sensor on the transmission housing.

4. 4

   Remove faulty sensor

   Disconnect the electrical connector from the sensor. Place a catch pan underneath to catch any transmission fluid that may leak, then unscrew and remove the faulty sensor.

5. 5

   Clean surface

   Clean the port and threads to remove all traces of oil, grease, and dirt according to SDF service guidelines.

6. 6

   Install new sensor

   Install the new sensor. If applying a thread-locking compound or sealant, ensure it forms a continuous film around the threads without entering the transmission housing. Tighten to the specified torque.

7. 7

   Reconnect wiring

   Reconnect the electrical connector to the new sensor.

8. 8

   Check fluid level

   Check the transmission oil level and top up any fluid lost during the sensor replacement.

9. 9

   Clear codes

   Reconnect the battery. Use the SERDIA diagnostic software (Level III interface is recommended) to clear the T12 fault code from the TCU memory.