Pontiac Fiero 1988 Service Manual page 394

CRANKING SYSTEM 6D2-1
SECTION 6D2
CRANKING SYSTEM
CONTENTS
General Description
6D2-1
Cranking System , 6D2-1
Starter Motor
6D2-1
Solenoid
6D2-1
Diagnosis
6D2-1
Cranking System 6D2-1
Service Procedures
6D2-3
Cranking System 6D2-3
On-Car Service
6D2-4
Starter
6D2-4
Specifications 6D2-11
Unit Repair 6D2-6-11
GENERAL DESCRIPTION
The engine electrical system includes the battery,
ignition (primary and secondary), starter (and related
wiring) and the generator (and related wiring).
Diagnostic charts (see Section 6D) will aid in
trouble-shooting system faults. When a fault is traced
to a particular component, refer to that components'
section of the service manual.
CRANKING SYSTEM
The cranking circuit consists of the battery,
starting motor, ignition switch, and related electrical
wiring. These components are connected electrically as
shown in Fig. 1.
Starter Motor
Wound field starter motors have pole pieces,
arranged around the armature, that are energized by
wound field coils.
Solenoid
Enclosed shift lever cranking motors have the
shift lever mechanism and the solenoid plunger
enclosed in the drive housing, protecting them from
exposure to dirt, icing conditions and splash.
In the basic circuit shown in Fig. 1, solenoid
windings are energized when the switch is closed. The
resulting plunger and shift lever movement causes the
pinion to engage the engine flywheel ring gear and the
solenoid main contacts to close, and cranking takes
place. When the engine starts, pinion overrun protects
the armature from excessive speed until the switch is
opened, at which time the return spring causes the
pinion to disengage. To prevent excessive overrun, the
switch should open immediately when the engine
starts.
DIAGNOSIS
CRANKING SYSTEM
Before removing any unit in a cranking circuit for
repair, the following checks should be made:
Electrical System General Diagnosis:
Follow the procedures shown in Section 6D to isolate
problem.
Battery:
To determine the condition of the
battery, follow the testing procedure outlined in the
Battery section (6D1).
Wiring:
Inspect the wiring for damage. Inspect
all connections to the cranking motor, solenoid,
ignition switch and battery, including all ground
connections. Clean and tighten all connections, as
required.
Solenoid and Ignition Switch:
Inspect all
switches to determine their condition.
Starter Motor Noise:
To correct starter motor
noise during starting, use the following procedure:
1. Refer to Fig. 2 to determine the problem.
2. If the complaint is noise, correction can be
achieved by proper "shimming" as follows:
a. Check flywheel for damage - bent flywheel,
unusual wear, etc.
b. Start engine and carefully touch outside
diameter of rotating flywheel ring gear with
chalk or crayon to show high point of tooth
runout. Turn engine off and rotate flywheel
so that the marked teeth are in the area of
the starter pinion gear.
c. Disconnect negative battery cable to
prevent cranking of engine.
d. Check pinion to flywheel clearance, as
shown in Fig. 3, by using a wire gage of
.5mm (.020") minimum thickness (or
diameter). Center a pinion tooth between
two flywheel teeth and gage, as shown in
Fig. 3. Do not gage in the corners, where a
misleading larger dimension may be
observed. If the clearance is under this
minimum, shimming the starter away from
the flywheel is required.
e. If the clearance is grossly over .5mm (.020")
in the vicinity of 1.5mm (.060") or more,
shimming the starter toward the flywheel is
required. (This is generally the problem
causing broken flywheel teeth or starter
housings,) Shimming the starter toward the
flywheel can be accomplished by shimming
only the outboard starter mounting pad. A
shim of <4mm (.015") thickness, at this