Buick LeSabre 1965 Service Manual page 603

ELECTRICAL SYSTEMS
IGNITION SYSTEM 1 0 - 3 3
SECTION 10-E
IGNITION SYSTEM
CONTENTS OF SECTION 10-E
Paragraph Subject Page
10-32 Ignition System Description
and Operation 10-33
10-33 Ignition System - Trouble
Diagnosis 10-36
10-34 Replacement and Adjustment
of Distributor Contact
Point Set 10-36
10-35 Ignition Timing 10-38
Paragraph Subject Page
10-36 Spark Plug and Wire Service . . . . 10-40
10-37 Ignition Coil T e s t s 10-41
10-38 Distributor Condenser T e s t s . . . . 10-42
10-39 Distributor Service
Operations 10-43
10-40 Ignition Switch and Lock
R e p a i r s 10-45
10-32 IGNITION SYSTEM
DESCRIPTION AND
OPERATION
a. Ignition System Components
The ignition system consists of
the ignition switch, ignition coil
resistance wire, ignition coil,
ignition distributor, spark plugs,
and the low and high tension wir-
ing. Electrical energy is obtained
from the battery while cranking
and from the generator after the
engine is running. These supply
circuits must be considered part
of the ignition system.
1. Ignition Switch. The ignition
switch has four positions: (1)
ACCESSORY, (2) LOCK, (3) ON,
and (4) START. The key must be
in the switch to turn it to any
position other than LOCK, and
the key can be removed only in
the LOCK position.
(a) In "ACC", a connection is
made from the battery terminal
to the accessory terminal of the
switch to allow accessories such
as the radio, blower and/or wind-
shield wiper to be operated with
the ignition, fuel gauge and indi-
cator light circuits off.
(b) In "LOCK", no accessory
supplied through the ignition
switch can be operated. Also, the
resistance wire circuit to the ig-
nition coil (IGN) i s grounded.
(c) In "ON", a connection is made
from the battery terminal to the
accessory terminal so that all
ignition switch supplied acces-
sories can be operated. Also the
battery is connected to the resist-
ance wire leading to the ignition
coil (IGN). From this s a m e
terminal, a lead into the instru-
ment cluster energizes the fuel
gauge and indicator lights.
(d) In "START", all i g n i t i o n
switch supplied accessories are
temporarily disconnected. A con-
nection is made to the starter
solenoid lead. The water temper-
ature light circuit is temporarily
grounded to provide a means of
checking the "TEMP." light bulb.
When the ignition switch is re-
leased, a s p r i n g returns it to
"ON".
2. Ignition Coil Resistance Wire.
The ignition coil resistance wire
is an integral part of the instru-
ment panel wiring harness. This
resistance wire is connected be-
tween the ignition switch and the
positive (+) terminal of the coil.
The resistance wire limits to a
safe maximum the primary cur-
rent flow through the coil and the
distributor contact points, thereby
protecting the contact p o i n t s
during slow speed operation when
they a r e c l o s e d for longer-
intervals. It also protects against
excessive build up of primary
current when the ignition switch
is closed with engine stopped and
contact points closed.
When the ignition switch is in the
"START" position, and the
starter is cranking, a connection
is made from starter solenoid
directly to the positive terminal
of the ignition coil, by-passing the
resistance. Elimination of the re-
sistance overcomes the effects of
reduced voltage due to cranking
motor drain on the battery.
3. Ignition Coil. The o i l filled
ignition coil is mounted on the
intake manifold, adjacent to the
ignition distributor. The positive
(+) terminal is connected to the
ignition switch through the re-
sistance wire, and is also con-
nected directly to the starter
solenoid to by-pass the resistance
wire during cranking of engine.
The negative (-) terminal is con-
nected to the distributor. The
secondary (high tension) terminal
is connected by a short cable to
the center terminal in the dis-
tributor cap.
4. Ignition Distributor. The igni-
tion distributor is of the external
adjustment type. It is d r i v e n
clockwise directly from the cam-
shaft through c a s t iron gears
which a r e automatically lubri-
cated by the engine oiling system.
Contact point opening is adjusted