Cessna T188C - Page 326

MODEL
188 & T188
SERIES SERVICE
MANUAL
16-33.
TROUBLE SHOOTING
THE ALTERNATOR
SYSTEM (14 VOLT
SYSTEM)
TROUBLE
PROBABLE
CAUSE
REMEDY
AMMETER
INDICATES
HEAVY
Shorted radio
noise filter
1. Remove cable
from output
DISCHARGE
WITH
ENGINE
or shorted wire.
terminal
of alternator.
Check
NOT RUNNING
OR ALTERNA-
resistance
from end
of cable
TOR CIRCUIT
BREAKER
OPENS
to ground
(MASTER
SWITCH
WHEN MASTER
SWITCH
IS
MUST
BE OFF).
If resistance
TURNED
ON.
does not
indicate
a direct
short,
proceed to step 4. If resistance
indicates a direct short, proceed
to step 2.
2. Remove cable connections
from
radio
noise filter.
Check
resistance
from
the filter
input
terminal
to
ground.
Normal
in-
dication is infinite resistance.
If reading
indicates
a
direct
short, replace filter. If no
short
is
evident,
proceed
to
step 3.
3. Check resistance from ground
to the free ends of the wires which
were connected to the radio noise
filter
(or alternator
if no
noise
filter
is installed).
Normal
indica-
tion does not show a direct short.
If a short
exists
in wires,
repair
or
replace
wiring.
Shorted
diodes
in
alternator.
4.
Check
resistance
from
output
terminal
of alternator
to alterna-
tor case.
Reverse
leads
and
check again.
Resistance
reading
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
SYSTEM
Regulator
faulty
or improp-
1.
Start
engine and
adjust
for 1500
WILL
NOT KEEP
BAT-
erly adjusted.
RPM.
Ammeter
should
indicate
a
TERY
CHARGED.
heavy
charge
rate with
all electri-
cal
equipment
turned
off. Rate
should
taper off
in 1-3 minutes.
A
voltage check at the bus should in-
dicate a reading consistant with the
voltage
vs temperature
chart
in the
Cessna Alternator Charging Systems
Service/Parts
Manual.
If charge
rate tapers
off very
quickly
and volt-
age is normal, check battery for
malfunction. If ammeter shows a
low charge rate or any discharge
rate, and voltage is low, proceed
to step 2.
16-22