Fendt 10.1.33 – A038 - Central Electrical System ECU: B074 - Sensor, internal temperature

The internal cab temperature sensor (B074) is non-operable. The signal is either absent, shorted, or out of the expected range, causing the air conditioning system to default to running in emergency mode.

• 922 Vario COM III
• 924 Vario COM III
• 927 Vario COM III
• 930 Vario COM III
• 933 Vario COM III
• 936 Vario COM III
• Fendt 300 Vario
• Fendt 400 Vario
• Fendt 700 Vario
• Fendt 800 Vario
• Fendt 900 Vario (including COM III, SCR, S4, and G6 generations)

1. 1

   Locate the B074 sensor inside the cab on the left mudguard within the ventilating shaft (accessible by removing the cab circulation air filter).

2. 2

   Inspect the wiring harness and the separation point connector (X1545) for corrosion, backed-out pins, or wire breaks.

3. 3

   Check the voltage supply at the sensor connector (e.g., pin F5 on X1409) using a multimeter. It should read 0 VDC with ignition OFF, and a 5.0 VDC reference voltage with ignition ON.

4. 4

   Connect the FENDIAS diagnostic tool and read the live data for the internal temperature sensor. An extreme default value (like -20°C or +50°C) indicates a faulty sensor or circuit.

1. 1

   Turn off the tractor ignition and ensure the electrical system is powered down.

2. 2

   Locate the cab circulation air filter housing on the left side of the cab (near the left mudguard).

3. 3

   Remove the cab circulation air filter to expose the ventilating shaft and gain access to the B074 sensor.

4. 4

   Locate the B074 internal temperature sensor and carefully disconnect its electrical connector (X1545).

5. 5

   Unclip or unscrew the faulty sensor from its mounting bracket in the ventilation shaft.

6. 6

   Install the replacement sensor and secure it in the exact same orientation.

7. 7

   Reconnect the electrical harness, ensuring the connector clicks securely into place.

8. 8

   Reinstall the cab circulation air filter and any protective covers.

9. 9

   Turn on the ignition and use the Varioterminal or FENDIAS tool to clear the stored 10.1.33 fault code.

10. 10

    Test the HVAC system to verify that the air conditioning has exited emergency mode and regulates temperature automatically.