Fendt 6.1.18 – Single E-box: A004 - 1000 rpm speed selector key — Key / A004 signal fault
Issue description
The system detects the 1000 rpm speed selector key (A004) has been pressed continuously for more than 30 seconds, indicating a mechanical fault (stuck button) or electrical fault (short circuit). The PTO speed cannot be modified normally, though 750 and 540 speeds can be selected by pressing the Engage PTO key for longer than 5 seconds.
Applies to these machines
52 machines- 409 Vario
- 410 Vario
- 411 Vario
- 412 Vario
- 711 Vario
- 712 Vario
- 714 Vario
- 715 Vario
- 716 Vario
- 717 Vario
- 718 Vario
- 916 Vario
- 920 Vario
- 924 Vario
- 926 Vario
- 930 Vario
- 411 Vario COM III
- 412 Vario COM III
- 413 Vario COM III
- 414 Vario COM III
- 415 Vario COM III
- 712 Vario COM III
- 714 Vario COM III
- 716 Vario COM III
- 718 Vario COM III
- 818 Vario COM III
- 820 Vario COM III
- Farmer 400
- 400 Vario
- 409
- 410
- 411
- 412
- Favorit 700
- 700 Vario
- 711
- 712
- 714
- 715
- 716
- 717
- 800 Vario
- 815
- 817
- 818
- Favorit 900
- 900 Vario
- 916
- 920
- 924
- 926
- 930
Check the cause
Inspect the A004 1000 rpm speed selector key on the side console for physical jamming, sticky debris, or a collapsed button
Disconnect the switch and test it with a multimeter for continuity to see if it is stuck in the closed position
Check the wiring harness between the A004 switch and the E-box for a short to ground or short to voltage
Repair steps
Power Down
Turn off the tractor and disconnect the battery to prevent electrical spikes.
Access the Switch
Remove the trim panels on the right-hand control console to access the rear of the PTO speed selector switch cluster.
Clean or Replace
If the switch is simply jammed by dirt or a spilled beverage, clean the housing with contact cleaner and ensure the button springs back freely. If the switch is internally shorted or mechanically broken, replace the A004 switch unit.
Repair Wiring
If the switch was fine but the harness was chafed and shorting out, repair the damaged wire and protect it with heat shrink or loom.
Reassembly & Clearing Codes
Reconnect the switch and battery. Turn the ignition on and use the tractor's terminal or the FENDIAS diagnostic tool to clear the stored 6.1.18 fault code.
Functional Test
Verify that you can freely toggle between 540, 750, and 1000 rpm speeds without the system locking out.
Parts you might need
(1)PTO 1000 rpm speed selector switch / key (A004)
Specific OEM part numbers depend heavily on the chassis number and whether the switch is a standalone rocker or integrated into a larger membrane keypad. Look up the specific chassis number in the Fendt AGCO Parts Catalog.
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