Fendt 04.1.87 – Transmission Control System: Plausibility error at the F/R (Forward/Reverse) switch, quick reverse

The tractor's control system detects an invalid or conflicting signal from the forward/reverse shuttle switch on the steering column. As a safety measure, the F/R switch becomes inoperable, and the Tractor Management System (TMS) may be switched off. The quick reverse function on the steering wheel adjustment lever is disabled.

• 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 (COM III / SCR)
• Fendt 400 Vario
• Fendt 500 Vario
• Fendt 700 Vario (e.g., 714, 716, 720, 724)
• Fendt 800 Vario (e.g., 819, 822, 824, 826, 828)
• Fendt 900 Vario (e.g., 927, 930, 933, 936, 939)

1. 1

   Test the physical actuation of the S079 quick reverse switch on the control stalk to ensure it clicks into forward, neutral, and reverse positions without sticking.

2. 2

   Inspect the wiring harness leading down the steering column, specifically checking connectors X1590 and X1591 for loose pins, corrosion, or wire chafing.

3. 3

   Verify the forward and reverse travel signals using a multimeter or diagnostic tool (like FENDIAS or TEXA) to check if the ECU is receiving simultaneous or missing signals.

1. 1

   Preparation

   Park the tractor on a level surface, apply the handbrake, turn off the ignition, and disconnect the battery to prevent electrical shorts.

2. 2

   Access the Switch

   Remove the plastic cowling/covers surrounding the steering column to expose the base of the control stalks.

3. 3

   Disconnect Wiring

   Locate the electrical connectors for the S079 steering column switch (connectors X1590/X1591) and carefully unplug them.

4. 4

   Remove the Faulty Switch

   Unscrew the mounting hardware securing the S079 switch assembly to the steering column and slide the stalk out.

5. 5

   Install the New Switch

   Mount the replacement OEM switch into position and secure it with the retaining screws.

6. 6

   Reconnect and Reassemble

   Plug the electrical connectors back in, ensuring they click securely into place. Reinstall the steering column covers.

7. 7

   Clear Codes and Test

   Reconnect the battery, turn on the ignition, and use the tractor's terminal or a diagnostic tool to clear the 04.1.87 fault code. Start the tractor and test the forward/reverse shuttle function to confirm the repair.