Kubota KX91-3a2 Operator's Manual page 95

Operation
1. Insert red key into the starter switch.
Do not turn the key at this point. If the key is in the
RUN position, turn it back to the STOP position.
2. Press the display selector switch.
3. The display shows the "Register mode - pull out red key"
message.
4. Pull out the red key.
5. The display shows the "Register mode - insert key" message.
6. Insert black key into the starter switch.
Do not turn the key at this point. If the key is in the
RUN position, turn it back to the STOP position.
7. The display shows the blinking "Register mode - insert key"
message.
8. After a brief moment, the display shows the "Finish - pull out
black key" message. This message indicates that the black
key was registered for the given vehicle.
9. Once the black key is pulled out of the starter switch, the display will show the "Finish - pull out black key"
message.
Follow steps 5 to 8 to register a spare key. Up to four black keys can be registered.
10. Turn the key to the RUN position to finish the registration procedure.
11. One after the other, insert all registered black keys into the starter switch and check whether the engine
can be started using these keys.
If a registered black key switch is lost, the other black key switches must be re-registered. This
procedure locks the lost or stolen black key, which can no longer be used to start the engine.
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