Buick LeSabre 1965 Service Manual page 599

ELECTRICAL SYSTEMS
SOLENOID TEST 1 0 - 2 9
will not sustain the voltage re-
quired to hold solenoid plunger
in after solenoid switch has been
closed.
3. If cranking motor spins and
drive pinion engages ring gear
but does not drive it, overrunning
clutch is slipping. Remove motor
to replace drive assembly.
4. If cranking motor does not
operate, note whether solenoid
plunger is pulled into solenoid
when solenoid circuit is closed.
Ordinarily the plunger makes a
loud click when it is pulled in.
If plunger is pulled in, solenoid
circuit is okay and trouble is in
solenoid switch, cranking motor,
or cranking motor circuit. The
cranking motor must be removed
for repairs to switch or motor
(par. 10-30).
5. If plunger does not pull into
solenoid when ignition switch is
turned to "START", the solenoid
circuit is open, or solenoid is
at fault.
6. To find reason why plunger
does not pull into solenoid, dis-
connect purple solenoid wire at
connector near battery terminal
block and press wire end against
post of terminal block. If cranking
motor operates, solenoid is okay;
trouble is in ignition switch, neu-
tral safety switch, or in wires and
SERIES COIL
BRUSH
COMMUTATOR
SHUNT
s
S HUNT
COIL
POLE SHOE
SERIES
COIL
Figure 10-27—Cranking Motor Circuits-
401 and 425 Engines
connections between these units.
7. As a final test, connect jumper
between solenoid battery terminal
and terminal on solenoid switch
to which purple wire is connected.
If cranking motor still does not
operate, remove motor for in-
spection and t e s t of solenoid
switch (par. 10-29).
b. Cranking Speed
Abnormally Low
Abnormally low cranking speed
may be caused by low battery or
defective cables, defective sole-
noid switch, defective cranking
motor, or an internal condition
of engine.
1. Make quick check of battery.
If low battery is indicated, test
battery (par. 10-9). If defective
cables are indicated, test cables
(par. 10-11).
2. If battery and cables are okay,
test cranking motor and solenoid
switch (par. 10-28).
3. If cranking motor and solenoid
switch test okay, the trouble is
due to an internal condition of
engine. This may be due to use
of engine oil which is too heavy
for prevailing temperatures.
10-27 PERIODIC
INSPECTION OF
CRANKING MOTOR
No periodic lubrication of the
cranking motor or solenoid is
required. The cranking motor and
brushes cannot be inspected with-
out disassembling the unit so no
service is required on the crank-
ing motor and solenoid between
inspection periods.
Cranking motor action is indica-
tive, to some extent, of the crank-
ing motor condition. A cranking
motor that responds readily and
cranks the engine at normal speed
when the control circuit is closed
is usually in good condition.
Check motor and solenoid switch
attaching bolts to make sure these
units are solidly mounted. Inspect
and manually check all wiring
connections at solenoid switch,
ignition switch, and neutral safety
switch. Make sure that all these
connections in the cranking motor
and control circuits are clean
and tight. It is advisable to test
the cranking circuit to make cer-
tain that excessive resistance
does not exist. See paragraph
10-28.
10-28 VOLTAGE TEST OF
CRANKING SYSTEM
AND SOLENOID
SWITCH
The voltage across the cranking
motor and switch while cranking
the engine gives a good indication
of any e x c e s s i v e resistance.
NOTE: Engine must be at normal
operating temperature when test
is made."
1. Inspect battery and cables
(par. 10-11) to make certain that
battery has ample capacity for
cranking and ignition.
2. Connect jumper wire to dis-
tributor terminal of coil and to
ground on engine, so that engine
can be cranked without firing.
3. Connect voltmeter positive (+)
lead to the motor terminal on
solenoid switch; connect voltmeter
negative (-) lead to ground on
starter. See Figure 10-28.
4. Turn ignition switch on, crank
engine and take voltmeter reading
as quickly as possible. If cranking
motor turns engine at normal
cranking speed with voltmeter
reading 9 or more volts, the
motor and switch are satisfac-
tory. If cranking speed is below
normal and voltmeter reading is
9 or greater, the cranking motor
is defective.
CAUTION: Do not operate crank-
ing motor more than 30 seconds
at a time without pausing to allow
motor to cool for at least two
minutes; otherwise, overheating