Starting System: Description and Operation
STARTER SYSTEMThe function of the starting system is to crank the engine at a sufficient speed to allow it to start. Heavy cables, connectors, and switches are used in the starting system because of the large amount of electrical current required by the starter motor while cranking the engine. The amount of resistance in the starting circuit must be kept to an absolute minimum to provide the maximum current for the starter motor operation. A discharged or damaged battery, loose or corroded connections, or partially broken cables will result in slower than normal cranking speeds and may also prevent the starter motor from cranking the engine.
NOTE: Engine oil viscosity can also affect engine cranking speed.
If the starter motor or starting circuit are suspected to be the cause of a no-start condition, use the Symptom Chart and diagnostic tests, to isolate the condition. Symptom Related Diagnostic Procedures
The starting system includes:
^ Permanent magnet gear-reduction starter motor
^ Starter solenoid
^ Battery
^ Ignition switch
^ Transmission Range (TR) sensor (CD4E)
^ Starter Clutch Pedal Position (SCPP) switch (MTX)
^ Heavy circuit wiring
Vehicles equipped with a manual transaxle have a SCPP switch. In order to energize the starter motor, the clutch pedal must be depressed to complete the starter motor circuit.
The shift control selector lever must be in the NEUTRAL or PARK position in order to complete the starter motor circuit.
Sequence of Operation
When the starter solenoid is energized, a magnetic field is created in the starter solenoid windings. The iron plunger core is drawn into the starter solenoid coil, and a drive lever connected to the starter drive engages the starter drive to the flywheel ring gear. When the plunger is pulled all the way in, its contact disk closes the circuit between the battery and starter motor feed terminals. This sends current to the starter motor, and the starter drive cranks the flywheel to start the engine. When current flows to the starter motor, the starter solenoid pull-in coil is bypassed, and the hold-in coil keeps the starter drive engaged with the flywheel until the ignition switch is released from the START position. An overrunning clutch in the starter drive protects the starter motor from excessive speeds during the brief period before the driver releases the ignition switch from the START position.