FORD 2005 F-550 v.1 - Manual (Page 89)

6. Press the unlock control, then press the lock control. The horn will
chirp once if autolock was deactivated or twice (one short and one long
chirp) if autolock was activated. Note: Pressing the power door
UNLOCK/LOCK button again will toggle between activating and
deactivating the autolock feature.
7. Turn the ignition to the 3 (OFF) position. The horn will chirp once to
confirm the procedure is complete.
REVIEW COPY
2005 F250/350/450/550 (f23), Owners Guide (post-2002-fmt) (own2002),
Market: USA_English (fus)
Locks and Security
89