Cessna 188 Series Service Manual page 321

MODEL 188 & T188 SERIES SERVICE MANUAL
16-29. TROUBLE SHOOTING.
TROUBLE PROBABLE CAUSE
REMEDY
STARTER ENGAGES WHEN
Shorted or reversed diode in
Check wiring to, and condition
GROUND POWER IS CON-
split bus-bar system. of diode mounted on the split
NECTED.
bus relay bracket adjacent to
the magneto switch. Correct
wiring. Replace diode board
assembly.
GROUND POWER WILL NOT
Ground service connector
1. Check for voltage at all
CRANK ENGINE.
wired incorrectly.
three terminals of external
power contactor with ground
power connected and master
switch off. If voltage is pre-
sent on input and coil termin-
als but not on the output ter-
minal, proceed to step 4. If
voltage is present on the input
terminal but not on the coil
terminal, proceed to step 2.
If voltage is present on all three
terminals, check wiring between
contactor and bus.
2. Check for voltage at small
terminal of ground service re-
ceptacle. If voltage is not pre-
sent, check ground service plug
wiring. If voltage is present,
proceed to step 3.
Open or mis-wired diode on
3. Check polarity and continuity
ground service diode board
of diode on diode board at rear
assembly.
of ground service receptacle.
If
diode is open or improperly wired,
replace diode board assembly.
Faulty external power con- 4. Check resistance from small
tactor. (coil) terminal of external power
contactor to ground (master switch
off and ground power unplugged).
Normal indication is 16-24 ohms.
If resistance indicates an open
coil, replace contactor. If
resistance is normal, proceed
to step 5.
Faulty contacts in external
5. With master switch off and
power contactor. ground power applied, check for
voltage drop between two large
terminals of external power
(turn on taxi light for a load).
Normal indication is zero volts.
If voltage is intermittently pres-
ent or present all the time,
replace contactor.
16-17