Fendt 0F.2.1C – A038 - ECU, central electrical system: Right trailer socket, terminal 58 faulty

The system has detected an electrical anomaly (such as an open circuit, short to ground, or short to power) on the circuit supplying terminal 58 at the rear trailer socket (designated as component X018). In standard European 7-pin trailer wiring, Terminal 58 is responsible for the right-hand tail lights, marker lights, and license plate illumination.

• 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 series
• Fendt 400 Vario series
• Fendt 500 Vario series (SCR)
• Fendt 700 Vario series (COM III, SCR)
• Fendt 800 Vario series (COM III, SCR, S4)
• Fendt 900 Vario series (COM III, SCR, S4)

1. 1

   Inspect the Trailer: If a trailer or implement was connected when the code triggered, disconnect it. Test the trailer's lighting board independently, as a short circuit in the trailer's wiring is the most common cause of this fault.

2. 2

   Visual Inspection of Socket (X018): Inspect the tractor's rear 7-pin trailer socket for physical damage, water ingress, heavy dirt, or green copper corrosion, specifically focusing on pin 58.

3. 3

   Wiring Harness Check: Trace the wiring harness from the rear trailer socket back toward the A038 Central Electrical System ECU. Look for pinched wires, chafing against the chassis, or melted insulation.

4. 4

   Voltage Test: Turn the tractor's lights on and use a multimeter to check for 12V output at terminal 58 on the tractor socket. If there is no voltage but the wiring is intact, the A038 ECU may have disabled the circuit to protect itself, or the internal driver in the ECU has failed.

1. 1

   Power Down

   Turn the ignition OFF and disconnect the tractor's battery to prevent accidental short circuits while working on the electrical system.

2. 2

   Remove the Socket

   Unscrew the mounting bolts holding the rear trailer socket (X018) to the bracket. Pull the rubber boot back to expose the wire terminals.

3. 3

   Clean or Repair Wiring

   If the wiring is corroded, cut the wires back to clean copper and strip the ends. If the socket is heavily corroded or physically broken, discard it.

4. 4

   Install New Socket

   Wire the new 7-pin socket according to the standard ISO 1185 / DIN 72577 diagram. Ensure the wire for the right tail light is securely fastened to terminal 58.

5. 5

   Seal the Connection

   Apply dielectric grease to the terminals to prevent future moisture ingress and reassemble the rubber boot and mounting hardware.

6. 6

   Test and Clear Codes

   Reconnect the battery, turn the ignition ON, and test the lighting circuit. Use the Fendt Vario terminal or FENDIAS diagnostic software to clear the stored 0F.2.1C fault code from the A038 ECU memory.