Good afternoon ya'll,

I ahve a Ford F150 2006. The check charging system light came on about 5 months ago. I changed the alternator and battery. Same day, the check system warning came on again. Took the alternator out and tested it, alternator was fine. Reinstalled it and the same warning comes on. The warning only comes on when I'm sitting still. When I acclerate it goes off.
any ideas?

 

Test the voltage while idling @ the battery.. should be 13.8vdc or more. have somebody rev your motor then back to idle and watch the voltage. Amp draw from the alternator is around 2.2