Chevrolet Impala 2018 Owner's Manual page 146

Normally, these actions occur in
steps or levels, without being
noticeable. In rare cases at the
highest levels of corrective action,
this action may be noticeable to the
driver. If so, a DIC message might
be displayed and it is recommended
that the driver reduce the electrical
loads as much as possible.
Battery Power Protection
The battery saver feature is
designed to protect the vehicle's
battery.
If some interior lamps are left on
and the ignition is turned off, the
battery rundown protection system
automatically turns the lamp off after
some time.
Exterior Lighting Battery
Saver
The exterior lamps turn off about
10 minutes after the ignition is
turned off, if the parking lamps or
headlamps have been manually left
on. This protects against draining
the battery. To restart the 10-minute
timer, turn the exterior lamp control
to the position and then back to
the or position.
To keep the lamps on for more than
10 minutes, the ignition must be on
or in ACC/ACCESSORY.
Lighting 145