Circuit Description

For ignition switch power modes refer to Body Control System Description and Operation . When the ignition switch is placed in the Start position a discrete 12 volts signal is supplied to the body control module (BCM) notifying it that the ignition is in the Start position. The BCM then supplies a class 2 message to the engine control module (ECM)/powertrain control module (PCM) notifying it that CRANK has been requested. At the same time the BCM is supplying 12 volts for the IGN 1 Relay/IGNITION MAIN PCM Relay closing it and supplying battery positive voltage for the CRANK Relay/STRTR Relay coil. The ECM/PCM verifies that the transmission is in Park or Neutral. If it is, the ECM/PCM grounds the control circuit of the CRANK Relay/STRTR Relay. When this occurs battery positive voltage is supplied through the switch side of the CRANK Relay/STRTR Relay to the S terminal of the starter solenoid. For remote vehicle start (RVS) information, refer to Keyless Entry System Description and Operation .