Textron Cessna 172R, Pilot Operating Handbook, Page: 252 / 500

SECTION 7
AIRPLANE & SYSTEMS
DESCRIPTION
CESSNA
MODEL 172R
The airplane uses
a
power distribution
module (J-Box),
located
on the left forward side of the
firewall,
to
house all relays used
throughout the airplane electrical system.
In addition, the alternator
control unit and the external
power
connector
are housed within the
module.
ANNUNCIATOR PANEL
An
annunciator panel (with integral
toggle
switch)
is located on
the
left
side of the instrument panel and provides caution (amber)
and warning
(red) messages for
selected portions of the airplane
systems.
The
annunciator is designed to flash messages for
approximately 10
seconds
to gain
the attention of the pilot before
changing
to
steady
on. The annunciator panel
cannot
be turned off
by the pilot.
Inputs to the annunciator
come
from
each
fuel transmitter,
the
low oil pressure switch, the vacuum transducers and the alternator
control unit
(ACU).
Individual LED bulbs illuminate each
message
and may be replaced through the
rear
of the annunciator.
Illumination intensity can be controlled by placing the toggle switch
in either the DIM or BRT positions (earlier serial number
airplanes)
or the DAY or NIGHT positions (later serial number airplanes).
The
annunciator panel can
be
tested by placing the Master
switch in the
ON
position and holding the annunciator panel
test
switch in the TST (earlier serial number airplanes) or the TEST
(later serial number airplanes) position. All amber and red
messages will
flash
until the switch is released.
NOTE
When the Master switch is turned
ON,
some annunciators
will
flash for
approximately
10
seconds
before illuminating
I
steadily. When the annunciator panel test switch is held in
the TST (earlier serial number airplanes)
or the TEST
(later
serial number
airplanes) position, all remaining lights will
flash
until the switch is released.
7-32
Revision
8
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