Starting System: Notes

The starting system consists of the following:

• Starter motor
• Starter motor relay
• Starter drive
• Battery
• Park/Neutral Position (PNP) switch (integral part of the mechatronics unit)
• Ignition switch
• PCM
• Start diode, part of the One-Touch Integrated Start (OTIS) system

The function of the starting system is to crank the engine at a speed fast enough to permit the engine to start. 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 and pin connected to the starter drive engages the drive pinion gear to the flexplate ring gear. When the plunger is pulled all the way in, the contact disc closes the circuit between the battery and the motor feed terminals. This sends current to the motor and the drive pinion gear cranks the flexplate 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 drive pinion gear engaged with the flexplate.

Automatic transmissions have a PNP  switch in the transmission. The PNP  switch prevents operation of the starter motor unless NEUTRAL or PARK is selected.