Deutz-Fahr T15 – Shuttle Control Unit: Operator presence sensor disconnected or shorting to ground

The control unit has detected that the operator presence sensor (seat sensor) is disconnected or shorting to ground (low voltage). This is a medium-priority safety circuit fault that typically inhibits tractor operations (such as PTO engagement or transmission movement) because the system cannot verify if the operator is safely in the seat.

• Agroplus 310, 320, 410, and 420 Profiline series tractors
• Deutz-Fahr Agrofarm series (410, 420, 430, 85, 100)
• Deutz-Fahr Agroplus models
• Deutz-Fahr Series 5D VSF CVT (T4i)
• Same Explorer 90 and R3 Evo models

1. 1

   Inspect the wiring harness between the seat and the ECU for chafing, breaks, or pinched wires that could cause a short to ground.

2. 2

   Check that the contacts on connector X130 of the shuttle control unit and connector X36 of the operator seat sensor are not loose, damaged, or corroded.

3. 3

   Verify the 5V power feed to the operator seat sensor.

4. 4

   Use a multimeter to check the sensor's continuity and signal level to determine if the switch itself has failed internally.

1. 1

   Switch the tractor off and remove the ignition key.

2. 2

   Locate the seat sensor wiring harness under the operator's seat and trace it to connector X36.

3. 3

   Disconnect connector X36 and inspect the pins.

   Clean any corrosion with electrical contact cleaner.

4. 4

   Trace the harness back to the Shuttle Control Unit (connector X130) and perform a continuity test on the wiring.

   This rules out a broken wire or a short to the chassis (ground).

5. 5

   Determine if the fault lies within the seat sensor mat/switch.

   This is the case if the wiring harness and 5V power supply are intact.

6. 6

   Remove the seat cushion to access the Grammer seat sensor mat.

7. 7

   Disconnect the faulty sensor and install the replacement OEM sensor mat.

8. 8

   Reassemble the seat cushion, reconnect connector X36, and turn the ignition on.

   Verify that the T15 code has cleared and tractor operations (like PTO and shuttle shifting) are restored.