Ford 2003 Mustang Workshop Manual page 2035

SECTION 303-06: Starting System
DESCRIPTION AND OPERATION
Starting System
Starter Motor
The starter motor is a 12-volt unit that has the starter solenoid mounted on the drive end housing and
functions as follows:
The current flows through the solenoid energizing coil until the solenoid plunger is at the end of
its travel.
The plunger closes a set of contacts that bypass the energizing coil, letting the holding coil keep
the starter drive engaged and passing starting current to the starter motor.
The motor is energized when the starter solenoid contacts are closed.
The starter drive engages the flywheel ring gear and starts the engine.
An overrunning clutch in the starter drive protects the starter motor from excessive speed when
the engine starts.
Starter Relay
The starter interrupt relay consists of:
pull in coil and contacts
When the ignition switch is in the START position:
the pull-in coil is activated and pulls the contacts together.
current passes through the starter relay from the engine compartment power distribution box to
the starter solenoid.
Clutch Pedal Position (CPP) Switch
The CPP switch for:
a manual transmission closes when the clutch pedal is depressed, completing the starting
circuit.
an automatic transmission is a jumper inserted in place of the CPP switch to complete the
circuit.
Starter System — Operation
When the ignition switch is turned to the START position the starter relay switches power to the starter
solenoid causing the starter motor to engage as long as:
the clutch pedal is depressed (manual transmission only).
the digital transmission range (TR) sensor is in PARK or NEUTRAL (automatic transmission
only).
2003 Mustang Workshop Manual