Cessna T188C - Page 329

MODEL
188
&
T188
SERIES
SERVICE
MANUAL
16-34.
TROUBLE
SHOOTING
THE
ALTERNATOR
SYSTEM
(28 VOLT
SYSTEM)'
a.
ENGINE
NOT
RUNNING.
TROUBLE
PROBABLE
CAUSE
REMEDY
AMMETER
INDICATES
HEAVY
Shorted
diode
in alternator.
Turn
off
Battery
Switch
and
re-
DISCHARGE
OR
ALTERNATOR
move
"B"
Lead
from
alternator.
CIRCUIT
BREAKER
OPENS.
Check
resistance
from
"B"
(Battery
Switch
ON,
Terminal
of
alternator
to
alter-
Alternator
Switch
OF
F,
nator
case.
Reverse
leads
and
all
other
electrical
check
again.
Resistance
reading
switches
OFF.
)
may show
continuity
in one
direc-
tion
but
should
show
an infinite
reading
in the
other
direction.
If
an
infinite
reading
is
not
ob-
tained
in
at
least
one
direction,
repair
or
replace
alternator.
ALTERNATOR
REGULATOR
Short
in Over-Voltage
sensor.
Disconnect
Over-Voltage
Sensor
CIRCUIT
BREAKER
OPENS
THRU
18803046
plug
and recheck.
If circuit
WHEN
BATTERY
AND
breaker
stays in
replace
Over-
ALTERNATOR
SWITCHES
Voltage
Sensor.
ARE
TURNED
ON.
Short
in alternator
voltage
Disconnect
regulator
plug and
regulator.
recheck.
If
circuit breaker
stays
in, replace
regulator.
Short
in alternator
field.
Disconnect
"F"
terminal
wire
and recheck.
If
circuit
breaker
stays
in,
replace
alternator.
b.
ENGINE
RUNNING.
ALTERNATOR
CIRCUIT
Defective
circuit
breaker.
Replace
circuit
breaker.
BREAKER
OPENS
WHEN
BATTERY
AND
ALTER-
NATOR
SWITCHES
ARE
TURNED
ON
OVER-
VOLTAGE
LIGHT
DOES
NOT
COME
ON.
ALTERNATOR
REGULATOR
Shorted
field
in
alternator.
Check
resistance
from
"F"
CIRCUIT
BREAKER
OPENS
terminal
of alternator
to
WHEN
BATTERY
AND
alternator
case,
if resistance
ALTERNATOR
SWITCHES
is less
than
5 ohms
repair/
ARE
TURNED
ON,
OVER-
replace.
VOLTAGE
LIGHT
DOES
NOT
COME
ON
ICAUTION
This
malfunction
frequently
causes
a shorted
regulator
which
will
result
in an
over-voltage
condition
when
system
is again
operated.
16-25