Deutz-Fahr I39 – Transmission / Hydraulic Shuttle Control Unit: Seat sensor cc Vcc

The operator presence sensor (seat switch) is reading 'out of range', specifically detecting a short circuit to Vcc (battery positive).

• Agroplus 310, 320, 410, and 420 Profiline series tractors
• Agrofarm 85-100
• Agrofarm 410/420/430
• Agrotron series
• SAME Explorer 90

1. 1

   Place the machine on a flat surface, chock the wheels, turn off the engine, and remove the ignition key.

2. 2

   Inspect the wiring harness leading to the seat suspension plate for pinched, chafed, or exposed wires that could be shorting to a 12V power source (Vcc).

3. 3

   Disconnect the seat sensor connector and use a multimeter to test the switch's continuity. The switch state should change cleanly when weight is applied to and removed from the seat.

4. 4

   With the sensor disconnected, check the machine-side connector to ensure there is no voltage bleeding into the sensor signal wire from a short in the main harness.

1. 1

   Park the tractor on a level surface, engage the parking brake, turn off the engine, and remove the key.

   Park the tractor on a level surface, engage the parking brake, turn off the engine, and remove the key.

2. 2

   Tilt or lift the seat cushion/suspension to access the operator presence switch located on the seat suspension plate.

   Tilt or lift the seat cushion/suspension to access the operator presence switch located on the seat suspension plate.

3. 3

   Disconnect the electrical connector from the faulty seat sensor.

   Disconnect the electrical connector from the faulty seat sensor.

4. 4

   If the diagnostic checks revealed a wiring short, repair the damaged section of the harness and insulate it properly.

   If the diagnostic checks revealed a wiring short, repair the damaged section of the harness and insulate it properly.

5. 5

   If the sensor itself is internally shorted to Vcc, unbolt/unclip the faulty seat switch from its mounting bracket.

   If the sensor itself is internally shorted to Vcc, unbolt/unclip the faulty seat switch from its mounting bracket.

6. 6

   Install the replacement seat sensor and secure it in place.

   Install the replacement seat sensor and secure it in place.

7. 7

   Reconnect the electrical harness.

   Reconnect the electrical harness.

8. 8

   Turn the ignition key to the ON position and verify that the I39 alarm code has cleared from the dashboard display. Test the PTO or shuttle controls to ensure the safety interlock is functioning correctly.

   Turn the ignition key to the ON position and verify that the I39 alarm code has cleared from the dashboard display. Test the PTO or shuttle controls to ensure the safety interlock is functioning correctly.