GMC 2003 Sierra - Manual (Page 170)

The DRL sysiem will dome csn when 1 he tallowing
concjitjors are met:
*, the igniiion am
* the exterior lamps control Is in AU7T3,
** the automatic transmission Is rwt In PARK [P)^ and
\ Ihe IlghI sensor determines it is daylime.
When the DRL pro on. only your DRL lamps will bo ori.
The lain amps, sidemarker and other tamps won’t be
on. The instrument panel won't be lit up eithar^
When it bepiits to get dark, the automatic headlamp
system will switch from DRL to the headlamps or the last
chosen headlamp setting that was used.
When you turn the headlamp switch off, the headlamps
will go off, and your DRL lamps will iHuminalo,
provided It is not dark ouliiide.
To Idle an automaiic transmi&&ior> equipped vehicle with
the DRL off, sel the parking brake. Shifting the
transmission Into PARK (P) will also allow you to idle
the vehicle with the DRL oft. The DRL will slay off until
you release tho parking brake or shift the iransmiasion
out of PARK (P).
To idle a manual transmission equipped vehide with the
DRL offf set thra parking brake. The DRL will slay off
until yiDu release Iho parkirrg brake*
Fog Lamps
If youf vehicia has tag lamps, use them for belter vision
in foggy Or misty conditions.
The tag lamp button Is
located on the left side of
your instrument panel.
Vour parking lamps and/or low-beam headlamps must
be on for your fog lamps to work.
Press tho button to turn the frig tamps on. Press the
button again to turn them oft. An indicator Ughl will glow
In the button when the fog lamps are on.
Remember, log lamps alone will not give off as much
lighl as your headlamps. Never use the fog tamps In Ihe
dark without lurning on the headlamps.
3-15