I'm not sure about later models, but there is a charge relay located on the passenger side panel in the cab, my alternator went to hell and it took this relay with it.  I bought a new alternator and nothing seemed to work, nobody new anything, so I traced the wiring to this relay, it was shot as well.  Threw everything in the trash and ran a 100amp delco three wire to the battery, I've never looked back at the toyotalectric blues.