Charging System Indicator
WARNING: This page is about a different car, the 2003 Mazda Tribute. However, it is still accessible from the selected car via links, so may be relevant.
On the 3.0L (4V) engine, the charging system indicator is hard-wired to the generator and illuminates when the generator output is insufficient to maintain the battery state of charge. On the 2.0L Zetec engine, the instrument cluster receives its signal from the PCM via the SCP (J1850) line.