Fendt A.1.94 – A057 - ECU, steering controller (Auto-Guide): S088 - Switch, Autoguide pressure: Short circuit in pressure switch signal line earth.

The system has detected that the electrical signal wire for the Auto-Guide steering pressure switch (component S088) is shorted to ground (earth).

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• 712 Vario COM III
• 714 Vario COM III
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1. 1

   Consult Wiring Diagram: Refer to Fendt electrical wiring diagram Sheet 39, which governs the Auto-Guide steering controller and pressure switch circuits.

2. 2

   Inspect the Harness: Trace the signal line from the S088 pressure switch back to the A057 steering controller ECU. Look for areas where the wire insulation may have rubbed through against the chassis or valve block, causing a short to ground.

3. 3

   Test the Switch: Disconnect the S088 switch. If the short to ground disappears on the ECU side of the harness but is present across the switch terminals, the switch has failed internally.

1. 1

   Park the tractor on a level surface, turn off the engine, and engage the handbrake.

2. 2

   Locate the S088 Auto-Guide pressure switch, which is typically mounted on the Auto-Guide steering valve block.

3. 3

   Disconnect the electrical harness from the S088 switch.

4. 4

   Using a multimeter, test the signal wire for continuity to ground.

5. 5

   If the wire is shorted to the chassis, repair the damaged section of the wiring harness and secure it away from pinch points.

6. 6

   If the wiring harness tests fine, unthread the faulty S088 pressure switch from the valve block and install a replacement switch.

7. 7

   Reconnect the electrical harness.

8. 8

   Clear the fault code from the tractor's memory.

   On the multiple display terminal, call up the fault code, then press and hold the confirm/delete buttons (often buttons A, B, and C simultaneously depending on the exact terminal version) until the code is cleared from the dashboard memory.

9. 9

   Test the Auto-Guide system to ensure the steering engages properly and the code does not return.