Buick 2003 Regal Owner's Manual page 118

A light sensor on top of the instrument panel makes the
DRL work, so be sure it isn't covered.
The DRL system will make your front turn signal lamps
come on when the following conditions are met:
The ignition is on,
the exterior lamps control is
off
and
the parking brake is released.
When the DRL are on, only your front turn signal lamps
will be on. The headlamps, taillamps, sidemarker and
other lamps won't be on. Your instrument panel won't be
lit up either.
When it's dark enough outside, your front turn signal
lamps will turn off and your vehicle's headlamps
and parking lamps will turn on. The other lamps that
come on with your headlamps will also come on.
When it's bright enough outside, your headlamps will go
off and your front turn signal lamps will come on.
To idle your vehicle with the DRL and automatic
headlamp control
off,
set the parking brake while the
ignition is in OFF or LOCK. Then start your vehicle. The
DRL, headlamps and parking lamps will stay
off
until
you release the parking brake.
To turn off the automatic headlamp feature when it's
dark outside, move the exterior lamp control to the
parking lamp position. Your parking lamps will remain
illuminated and your headlamps will turn
off.
The fog
lamps will also be lit if they were on when you switched
to the parking lamp position.
As with any vehicle, you should turn on the regular
headlamp system when you need it.
Delayed Headlamps
Delayed headlamps illumination provides a period of
exterior lighting as you leave your vehicle. The feature is
activated when your vehicle's headlamps are on due
to the automatic headlamp control feature described
previously in this section, and when your vehicle's
ignition is turned
off.
Your headlamps will then remain
on until the exterior lamps control is moved from OFF to
the parking lamp position or until a 90 second lighting
period has ended.
If you turn off the ignition with the exterior lamps control
in the parking lamp or headlamps position, the delayed
headlamps illumination cycle will not occur.
You can customize the vehicle to activate delayed
headlamps illumination when your vehicle's ignition is
turned off under the conditions described above, or you
may choose not to activate this feature under any
conditions.
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