Circuit Description

WARNING: This page is about a different car, the 2005 Buick LaCrosse and 2005 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.

The ignition 1 relay is controlled by the body control module (BCM). The ignition 1 relay contacts are supplied a hot at all times from the fuse block underhood. The relay supplies power to several components when the vehicle is in the RUN or CRANK power mode. When the ignition switch is placed in the RUN or CRANK position, the BCM will receive an ignition 1 signal from the ignition switch and turn ON the ignition 1 relay. When the ignition switch is in the OFF position, the BCM will turn OFF the ignition 1 relay. The powertrain control module (PCM) compares the ignition 1 relay output signal with the BCM class 2 serial data power mode message. If the ignition 1 voltage signal and the power mode message do not match for an allotted time, the PCM will disable the fuel injectors and DTC P2535 will set.