This is the stupidity that is GM engineering, instead of just using the ignition switch to trigger the starter solenoid directly, or via a single relay, GM electrical engineers decided for some reason that they needed a dual relay setup to the starter, where the power goes through both relays before it hits the starter signal wire. The ignition line in the steering wheel is pulled low by the push button, which activates the relays and sends the control signal to the pin on the starter motor, engaging the solenoid and spinning the motor.
The reason for 2 separate 12V supplies is just to show the wiring of the relay, they both get tied to the same 12V source.
Blue = Starter Motor Fuse
Green = Starter Relay Fuse
Orange = From Ignition Signal Wire
Red = To Starter Signal Wire
