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Principles Of Operation




Starting System

Principles of Operation

The starting system is electronically controlled by the PCM. The PCM receives the following inputs:

- Brake pedal pressed, from the brake position switch, all vehicles
- Transmission in PARK or NEUTRAL, from the Transmission Range (TR) sensor, vehicles with automatic transmission
- Clutch pedal applied, from the Clutch Pedal Position (CPP) switch, vehicles with manual transmission
- Transfer case in NEUTRAL, from the 4X4 control module, Four-Wheel Drive (4WD) equipped vehicles
- Correctly coded ignition key, from the Passive Anti-Theft System (PATS), vehicles equipped with PATS
- Starter motor request, ignition switch in the START position, late build vehicles

When the ignition switch is placed in the START position, voltage is supplied to the coil of the starter relay through the One-Touch Integrated Start (OTIS) diode. A starter motor request signal is also sent to the PCM. If the PCM recognizes the needed input signals, it provides the starter relay coil with both voltage and ground. The starter relay contacts close, providing voltage to the starter solenoid, allowing the starter motor to activate. Once the starter motor begins to crank, the ignition switch may be released. The starter motor will continue to crank until the engine starts, the timing circuit in the PCM times out or the ignition switch is placed in the OFF position. OTIS is disabled on manual transmission equipped vehicles. Therefore, on these vehicles, the starter will stop cranking when the ignition switch is released from the START position.