Circuit Description
WARNING: This page is about a different car, the 2003 Buick Regal, 2003 Buick Century, 2002 Buick Regal, and 2002 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
Moving the ignition switch to the Start position sends a 12-volt signal through the Crank Signal BCM, Cluster fuse in the I/P Fuse Block, to the BCM, IPC, and PCM to notify these modules that a crank status has been requested. At the same time 12 volts is fed through the PCM BCM U/H Relay fuse in the I/P Fuse Block to the coil side of the CRANK relay. The PCM grounds this circuit when all parameters are met for starting the engine. This closes the CRANK relay allowing Battery Positive voltage through the CRANK fuse and CRANK relay in the Underhood Fuse Block then through the Park/Neutral Position Switch to the S terminal of the starter solenoid. Ground is found through the engine block.