Circuit/System Description

WARNING: This page is about a different car, the 2019 Buick Cascada, 2018 Buick Cascada, and 2017 Buick Cascada. However, it is still accessible from the selected car via links, so may be relevant.

The body control module (BCM) controls the ignition main (underhood), ignition main (rear body), ignition run, and retained accessory power relays by applying voltage to their individual relay control circuits. The ignition main (underhood) and ignition main (rear body) relays are energized when the ignition is in the ON or the CRANK position. The ignition run relay is energized when the ignition switch is in the ACCESSORY or the ON position. The retained accessory power relay is energized during all power modes, except OFF-awake and CRANK. The relay is also energized for approximately 10 min after shutting the ignition OFF, providing no door is opened.

The engine control module (ECM) controls the engine controls the ignition relay by applying voltage to the engine controls relay control circuit.