Cessna 177 SERIES Service Manual page 266

3
16-39. TROUBLE SHOOTING THE ALTERNATOR SYSTEM (THRU 1977 MODELS) (CONT.)
TROUBLE PROBABLE CAUSE
REMEDY
ALTERNATOR SYSTEM
Regulator faulty or improp-
2. Stop engine, remove cowl,
WILL NOT KEEP BAT-
erly adjusted.
(cont) and remove cover from voltage
TERY CHARGED. (cont)
regulator.
Turn master switch
ON/OFF several times and ob-
serve field relay in regulator.
Relay should open and close with
master switch and small arc
should be seen as contacts open.
If relay is inoperative, proceed
to step 3. If relay operates,
proceed to step 4.
3. Check voltage at "S" terminal
of regulator with master switch
closed. Meter should indicate bus
voltage. If voltage is present, re-
place regulator. If voltage is not
present, check wiring between
regulator and bus.
4. Remove plug from regulator
and start engine. Momentarily
jumper the "A+" and "F" termi-
nals together on the plug. Ship's
ammeter should show heavy rate
of charge. If heavy charge rate
is observed, replace regulator.
If heavy charge rate is not ob-
served, proceed to step 5.
5. Check resistance from "F"
terminal of regulator to "F" ter-
minal of alternator.
Normal
indication is a very low resis-
tance. If reading indicates no,
or poor continuity, repair or
replace wiring from regulator
to alternator.
6. Check resistance from "F"
terminal of alternator to alter-
nator case. Normal indication
is 6-7 ohms. If resistance is
high or low, repair or replace
alternator.
7. Check resistance from case
of alternator to airframe ground.
Normal indication is very low
resistance. If reading indicates
no, or poor continuity, repair or
replace alternator ground wiring.
ALTERNATOR OVERCHARGES
Regulator faulty or improperly Check bus voltage with engine run-
BATTERY - BATTERY USES adjusted,
ning. Normal indication agrees with
EXCESSIVE WATER.
the Cessna Alternator Charging sys-
tem Service/Parts Manual. Observe
ship's ammeter, ammeter should
indicate near zero after a few min-
utes of engine operation. Replace
regulator.
Change 7
16-11