Normal Operation
WARNING: This page is about a different car, the 2004 Mercury Mountaineer and 2004 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.
Under normal operation, the I (ignition) circuit 904 (LG/RD) will be 6-8 volts (C102a connected) with the key in the ON position and the engine not running. This will cause the charging system warning indicator to turn on. This circuit is also used to turn the charging system warning indicator on if there is a fault in the charging system.