Deutz-Fahr T73 – Transmission / Hydraulic Control Unit (TCU): Clutch Comfort button fault

The control unit detects that the Comfort Clutch push button on the gear lever is shorting to ground. The system interprets this electrical short as the button being continuously pressed, which disables or disrupts the automatic clutch modulation used for shifting gears without the foot pedal.

• Agroplus 310, 320, 410, and 420 Profiline series tractors
• Agrofarm Series (410, 420, 430, Agrofarm G)
• Agrotron Series (6 Series: 6135G, 6155, 6205; M Series, K Series)
• 5 Series
• Agroplus Series (V/S/F)

1. 1

   Check the red Comfort Clutch button on the gear lever to ensure it is not physically jammed, sticky, or collapsed into the handle.

2. 2

   Remove the gear lever trim/boot to expose the wiring and disconnect the button's electrical connector.

3. 3

   Test the button itself with a multimeter. If there is continuity across the button's pins while it is not being pressed, the button is internally shorted.

4. 4

   Check the signal wire leading from the gear lever connector down to the Transmission ECU for chafed insulation, pinched wires under the side console/armrest, or a short to ground.

5. 5

   Inspect the ECU pins and the inline connectors at the base of the gear lever for moisture, corrosion, or bent pins.

1. 1

   Disconnect Power

   Turn off the tractor ignition and disconnect the negative battery terminal to prevent electrical spikes.

2. 2

   Access the Switch

   Carefully pry off the gear lever cap or remove the screws securing the gear knob halves (depending on your specific series handle design) to access the Comfort Clutch button and its wiring.

3. 3

   Remove the Faulty Component

   Disconnect the micro-switch/button from the sub-harness. If the button is integrated into a sealed gear knob, you will need to remove the entire knob assembly by loosening the set screw or retaining nut at the base of the knob.

4. 4

   Repair Wiring (If Applicable)

   If the diagnostic tests revealed a chafed wire in the lever stalk rather than a bad button, splice and heat-shrink the damaged wire, ensuring it is routed away from pinch points.

5. 5

   Install the New Part

   Plug the new push button or gear knob assembly into the harness. Secure it back onto the gear lever stalk.

6. 6

   Reassemble and Reconnect

   Reassemble the gear lever trim and reconnect the battery.

7. 7

   Clear Codes and Test

   Turn the ignition on. The active fault may clear itself once the short is removed, but you may need a diagnostic tool (like TEXA or Deutz-Fahr SERDIA) to clear the stored T73 code. Test drive the tractor to verify that you can shift gears smoothly using the Comfort Clutch button without using the foot pedal.