Cadillac 2011 DTS Owner's Manual page 188

For vehicles with footwell lamps, they are located under
the instrument panel and at the rear of the front seats.
These lamps provide soft light to the front and rear floor
areas. They dim with the instrument panel cluster lights.
Footwell lighting brightness can be adjusted with the
instrument panel brightness control located below the
exterior lamps control. See Instrument Panel Brightness
on page 4 29. The footwell lights will turn off before the
instrument panel lights are at their lowest level of
brightness.
This feature monitors the vehicle's electrical load and
determines when the battery is in a heavy discharge
condition. During times of high electrical loading, the
engine may idle at a higher revolutions per minute (rpm)
setting than normal to make sure the battery charges.
High electrical loads may occur when several of the
following are on: headlamps, high beams, fog lamps,
rear window defogger, the climate control fan at high
speeds, heated seats and engine cooling fans.
If the battery continues to discharge, even with the
engine idling at a higher rpm setting, some electrical
loads will automatically be reduced. When this occurs,
the rear window defogger may take slightly longer to
clear the glass, the heated seats may not get as warm
4-30
as they usually do and the climate control fan may cut
back to a lower speed. For more battery saving
information, see Battery Saver Active Message under
DIC Warnings and Messages on page 4 62.
The vehicle has Electric Power Management (EPM) that
estimates the battery's temperature and state of charge.
It then adjusts the voltage for best performance and
extended life of the battery.
When the battery's state of charge is low, the voltage
is raised slightly to quickly bring the charge back up.
When the state of charge is high, the voltage is lowered
slightly to prevent overcharging. If the vehicle has a
voltmeter gauge or a voltage display on the Driver
Information Center (DIC), you may see the voltage
move up or down. This is normal. If there is a problem,
an alert will be displayed.
The battery can be discharged at idle if the electrical
loads are very high. This is true for all vehicles. This is
because the generator (alternator) may not be spinning
fast enough at idle to produce all the power that is
needed for very high electrical loads.
A high electrical load occurs when several of the
following are on, such as: headlamps, high beams, fog
lamps, rear window defogger, climate control fan at high
speed, heated seats, engine cooling fans, trailer loads,
and loads plugged into accessory power outlets.