Starting System: Description and Operation

GENERAL INFORMATION

Starting System Components:

The starting system has:
- Ignition switch
- Starter relay
- Transmission range sensor, or Park/Neutral Position switch with automatic transmissions
- Clutch Pedal Position Switch with manual transmissions
- Wiring harness
- Battery
- Starter motor with an integral solenoid
These components form two separate circuits. A high amperage circuit that feeds the starter motor up to 300+ Amps, and a control circuit that operates on less than 20 Amps.

SYSTEM OPERATION
Bosch And Melco Starters
The Bosch and Melco are permanent magnet starter motors. A planetary gear train transmits power between starter motor and pinion shaft. The fields have six permanent magnets. The Melco engine is used.


Nippondenso Starter
The Nippondenso is a reduction gear-field coil starter motor.

Supply Circuit And Control Circuit
The starter system consists of two separate circuits:
- A high amperage supply to feed the starter motor.
- A low amperage circuit to control the starter solenoid.

CIRCUIT OPERATION
The Power Distribution Center ([1][2]PDC) supplies battery voltage to the engine starter motor solenoid through circuit T40 when the coil side of the engine starter motor relay energizes. Circuit A1 contains a 20 Amp fuse, and feeds the contact side of the engine starter motor relay. Both the 20 Amp fuse and the engine starter motor relay are located in the PDC.

The ignition switch supplies battery voltage to the coil side of the engine starter motor relay on circuit A41 when the key is moved to the START position and the PARK/NEUTRAL portion of the Transmission Range Sensor (TRS) is CLOSED. Circuit A41 also provides an ignition start input to the Transmission Control Module (TCM).

Ground for the coil side of the engine starter motor relay is supplied on the T41 circuit by the TRS, which is case-grounded. The T41 circuit is also an input to the Powertrain Control Module (PCM), cavity 76, and the TCM, cavity 41. This input is used to indicate when the vehicle is in the PARK or NEUTRAL positions.

Circuit A0 (battery positive cable) supplies battery voltage to the engine starter motor when the solenoid energizes. Ground for the engine starter motor is supplied through the starter motor case.