Possible Causes

WARNING: This page is about a different car, the 2003 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

Possible causes are:

Generator malfunction
PCM and/or generator are poorly connected
Short circuit to power in Green wire between generator 2-pin harness connector terminal "D" and PCM 30-pin harness connector terminal "1AD"