Battery Power Protection - GMC Yukon XL Denali Owner's Manual

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.
EPM works to prevent excessive
discharge of the battery. It does this
by balancing the generator's output
and the vehicle's electrical needs.
It can increase engine idle speed to
generate more power, whenever
needed. It can temporarily reduce
the power demands of some
accessories.
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 Driver Information
Center (DIC) message might be
displayed, such as BATTERY LOW
START VEHICLE . If this message
displays, it is recommended that the
driver reduce the electrical loads as
much as possible and restart the
vehicle. See Battery Voltage and
Charging Messages on page 5 35.
Lighting

Battery Power Protection

This feature shuts off the dome, and
reading lamps if they are left on for
more than 10 minutes when the
ignition is off. This will keep the
battery from running down.
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