Deutz-Fahr I 22 – Instrument Panel (Infocenter) / Transmission ECU / Vehicle Control Unit (VCU): Frequency sensor 2 not connected / Instrument panel does not receive the D+ signal from the alternator

The fault code I 22 translates to 'Frequency sensor 2 not connected' or 'Instrument panel does not receive the D+ signal from the alternator.' Note: Operator Seat Switch logic errors are typically logged under a different code (such as U17, 2009, or 2010) in the Transmission ECU or VCU, not as I 22.

• 5 Series 5090
• 5100
• 5110
• 5120 C
• Agrofarm
• Virtus J
• Agrotron
• 5 Series
• 6 Series
• 7 Series
• 9 Series

1. 1

   (For I 22 Alternator D+ Signal) Check the D+ terminal connection directly at the alternator to ensure it is secure and free of corrosion.

2. 2

   (For I 22 Alternator D+ Signal) Inspect the wiring harness running from the alternator to the Infocenter for chafing, breaks, or rodent damage.

3. 3

   (For I 22 Alternator D+ Signal) Measure the voltage at the D+ terminal with the engine running; it should show charging voltage (~13.5V - 14.4V).

4. 4

   (For I 22 Alternator D+ Signal) Verify the Infocenter configuration using the SDF Analyser diagnostic tool to ensure it is programmed for the correct alternator setup.

5. 5

   (For Seat Switch Logic) Inspect the wiring harness under the operator's seat for pinched or chafed wires caused by the suspension mechanism.

6. 6

   (For Seat Switch Logic) Disconnect the seat switch and test continuity with a multimeter to ensure it toggles cleanly between open and closed states when weight is applied.

7. 7

   (For Seat Switch Logic) Check for a blown fuse related to the cab controls or seat suspension circuit.

1. 1

   Disconnect battery

   (For I 22 Alternator D+ Signal Loss) Disconnect the negative battery terminal.

2. 2

   Clean alternator contacts

   (For I 22 Alternator D+ Signal Loss) Locate the alternator and remove the connector for the D+ wire. Clean the contacts with electrical contact cleaner.

3. 3

   Repair wiring

   (For I 22 Alternator D+ Signal Loss) If a break in the wire is found between the alternator and the cab bulkhead, cut out the damaged section and solder in a new piece of automotive-grade wire, sealing it with heat-shrink tubing.

4. 4

   Replace alternator

   (For I 22 Alternator D+ Signal Loss) If the wiring is intact but the alternator is not outputting the D+ signal, replace the alternator.

5. 5

   Verify repair

   (For I 22 Alternator D+ Signal Loss) Reconnect the battery, start the engine, and verify the I 22 code clears from the Infocenter.

6. 6

   Prepare tractor

   (For Operator Seat Switch Replacement) Park the tractor on a level surface, apply the parking brake, and turn off the ignition.

7. 7

   Access switch

   (For Operator Seat Switch Replacement) Tilt the seat forward or remove the bottom seat cushion (depending on the seat brand) to access the presence switch located in the base.

8. 8

   Disconnect harness

   (For Operator Seat Switch Replacement) Disconnect the electrical harness from the switch.

9. 9

   Remove switch

   (For Operator Seat Switch Replacement) Unclip or unbolt the faulty switch from the seat pan.

10. 10

    Install switch

    (For Operator Seat Switch Replacement) Install the new seat switch.

11. 11

    Route wiring

    (For Operator Seat Switch Replacement) Crucial Step: Route the new wiring harness carefully, securing it with zip ties away from the scissor-action suspension mechanism to prevent future pinching.

12. 12

    Verify repair

    (For Operator Seat Switch Replacement) Reconnect the harness, turn on the ignition, and verify the transmission will now engage forward/reverse without throwing a plausibility error.