Circuit Description

WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.

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 sends 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 .