Dodge RAM TRUCK 1500 1995 Service Manual page 344

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BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS 8A -11
S T A R T I N G S Y S T E M
GENERAL INFORMATION
The starting system (Fig. 11) consists of:
• ignition switch
• starter relay
• park/neutral position switch (automatic transmis­
sion)
® clutch pedal position switch (manual transmission)
• wiring harness and connections
• battery
• starter with an integral solenoid.
SOLENOID TERMINAL
NEGATIVE
IGNITION
SWITCH
CLUTCH PEDAL
POSITION SWITCH
(MAN. TRANSMISSION ONLY)
GROUND,
CIRCUIT
PARK/NEUTRAL POSITION
SWITCH (AUTO.
TRANS. ONLY)
THIS CIRCUIT GROUNDED
AT ALL TIMES
(MAN. TRANS. ONLY)
958A-T
Fig, 11 Starting System Components - Typical
Following is a general description of the major
starting system components. Refer to Group 8W -
Wiring Diagrams for complete circuit descriptions
and diagrams.
These components form 2 separate circuits. A high-
amperage feed circuit that feeds the starter up to
300+ amps (700 amps-diesel engine), and a low-am­
perage control circuit that operates on less than 20
amps.
If the vehicle is equipped with an automatic trans­
mission, battery voltage is supplied through the low-
amperage control circuit to the coil battery terminal
of the starter relay when the ignition switch is
turned to the START position. If the vehicle is
equipped with a manual transmission, it also has a
clutch pedal position switch. The clutch pedal posi­
tion switch supplies battery voltage to the coil bat­
tery terminal of the starter relay only if the clutch
pedal is depressed while the ignition switch is turned
to the START position.
If the vehicle is equipped with an automatic trans­
mission, the park/neutral position switch provides a
ground path to the starter relay coil ground terminal.
This switch provides ground only with the transmis­
sion in NEUTRAL or PARK. If the vehicle is
equipped with a manual transmission, the starter re­
lay coil ground terminal is always grounded.
With the starter relay coil now energized, the nor­
mally open relay contacts close. The relay contacts
connect the relay common feed terminal to the relay
normally open terminal. The closed relay contacts en­
ergize the starter solenoid coil windings.
The energized solenoid coils pull-in and hold-in the
solenoid plunger. The solenoid plunger pulls the shift
lever in the starter. This engages the starter overrun­
ning clutch and pinion gear with the flywheel/drive
plate ring gear.
As the solenoid plunger reaches the end of its
travel, the solenoid contact disc completes the high-
amperage starter feed circuit. Current now flows be­
tween the solenoid battery terminal and the starter
motor, energizing the starter.
Once the engine starts, the overrunning clutch pro­
tects the starter from damage by allowing the starter
pinion gear to spin faster than the pinion shaft.
When the driver releases the ignition switch to the
ON position the starter relay coil is de-energized.
This causes the relay contacts to open. When the re­
lay contacts open, the starter solenoid coil is de-ener­
gized.
When the solenoid coil is de-energized, the solenoid
plunger return spring returns the plunger to its re­
laxed position. This causes the contact disc to open
the starter feed circuit, and the shift lever to disen­
gage the overrunning clutch and pinion gear from the
ring gear.
The starter motor and solenoid are serviced only as
a complete assembly. If either component fails, the
entire assembly must be replaced.
DIAGNOSIS
Before removing any unit from the starting system
for repair, perform the following inspections:
INSPECTION
BATTERY IlSPECTiOl
To determine condition of the battery, see Battery
in this group.