I made a brief video on the procedure I have used for many years here at the dealer that has not failed me yet in identifying a weak but functioning alternator causing many headaches like no starts after changing the battery and only checking the voltage output of the Alt. I hope this helps as there really isn't a need to take the alt off to get it tested. No fancy tools required.

 

I could have used this about a year ago with my F-150. The alternator registered at the auto parts store as functioning using their diagnostic equipment, but it was indeed the problem. Thanks for sharing!

 

Nice just goes to show taking it off the be load tested isnt always the solution.

 

The auto parts 'dummy' equipment is mediocre at best. I went their last week to test my battery. Tested OK, as did my alternator and starter. Ran the test again, car wouldn't start, only click. Test still showed all three ok. Turned out starter was bad even though it showed up as good.