Fast Idle System - GMC Sierra 2015 Owner's Manual

Caution (Continued)
the cranking motor, and drain the
battery. Wait at least 15 seconds
between each try, to let the
cranking motor cool down.
2. If the engine does not start after
five to 10 seconds, especially in
very cold weather (below 18°
C or 0°F), it could be flooded
with too much gasoline. Try
pushing the accelerator pedal all
the way to the floor and holding
it there while holding the key in
START for up to 15 seconds.
Wait at least 15 seconds
between each try, to allow the
cranking motor to cool down.
When the engine starts, let go of
the key and accelerator. If the
vehicle starts briefly but then
stops again, do the same thing.
This clears the extra gasoline
from the engine. Do not race the
engine immediately after starting
it. Operate the engine and
transmission gently until the oil
warms up and lubricates all
moving parts.

Fast Idle System

If equipped, this feature is available
only with cruise control. The manual
fast idle switch is operated using the
cruise control buttons on the left
side of the steering wheel.
This system can be used to
increase engine idle speed
whenever the following conditions
are met:
The parking brake is set.
The brake pedal is not pressed.
The vehicle must not be moving
and the accelerator must not be
pressed.
To control the fast idle:
To enable the Fast Idle System,
press and release the cruise
control on/off button and ensure
that the switch indicator light
is lit.
Driving and Operating
Press and release the cruise
control SET- button. Engine
speed will be held at
approximately 1200 rpm.
One of the following actions will turn
off the fast idle:
Pressing the brake.
Selecting the cruise control
cancel button.
Releasing the parking brake.
Moving the transmission shift
lever out of P (Park) or
N (Neutral).
Selecting the cruise control on/
off button when it was
previously on.
Pressing the cruise control SET-
button a second time.
Pressing the accelerator more
than one-quarter of the
way down.
Turning the ignition switch to the
LOCK/OFF position.
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