Ignition ON Input Signal

The body control module (BCM) uses this input signal to determine when the ignition switch is turned to the ignition or to the start position. When this occurs battery voltage via the ignition switch is applied to the BCM. When the BCM receives an ignition ON input signal, it energizes the Power Window Relay by grounding the relay coil. With the relay energized, the relay contacts close and power is applied to the power window switches. The opposite side of each window switch LED is connected to ground, causing the LEDs to illuminate, thereby indicating that the power window electrical system is active.