Circuit/System Description
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The engine control module (ECM) controls engine cranking based on a power mode input and the status of the park/neutral position (PNP) switch. With the transmission in Park/Neutral, voltage at the ECM PNP switch signal circuit is low. This indicates to the ECM that conditions are acceptable for cranking. When a power mode crank request is seen, the ECM applies voltage to the STRTR relay coil control circuit. This energizes the coil side of the relay, which pulls the switch side of the relay closed, applying voltage to the starter terminal S X2 and engaging the starter solenoid.