Starting System: Description and Operation

Fig. 1 Starting System Schematic:

STARTING SYSTEM
The starting system has (Fig. 1):
- Ignition switch
- Starter relay
- Transmission Range Sensor or Park/Neutral Switch
- Wiring harness
- Battery
- Starter motor with an integral solenoid
- Powertrain Control Module (PCM)

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.

The PCM controls a double start over-ride safety that does not allow the starter to be engaged if the engine is already running.

STARTER
The Denso is a wound field starter motor. It uses an integral non-serviceable solenoid. It is attached to the driver's side of the engine bolted to the bell housing.

When the starter relay is energized, the solenoid contacts close. A planetary gear train transmits power between starter motor and pinion shaft. The fields have permanent magnets.

STARTER RELAY
The Starter Relay is a micro relay located in the Power Distribution Center (PDC), positioned in the left side of the engine compartment.

As battery power is applied to the relay from the ignition switch, battery power is applied to the starter motor through the relay to the starter solenoid.

The starter relay ground is provided by the PCM. When the park/neutral switch contacts are closed, indicating Park or Neutral, the PCM will supply the ground path for the starter relay at key ON. This will occur if the engine RPM is below a predetermined value.

STARTER SOLENOID
The Starter Solenoid is mounted directly to the Starter Motor, mounted on the left side of the engine.

The Starter Solenoid is a switching device used to activate the high amperage starter motor circuit from a low amperage control circuit.