2004 F150 XLT 5.4 lights got dim and truck started missing what is the best way to test out the alternator to see if its bad a eazy way I don't know much about working on them .Thanks

 

Do you have a voltmeter? If so while your trucks off hook it up ( red on red black on black ) and see what juice it's puttin out. Should be about 12 volts or so.. If you're not getting that then get your battery tested or just try some other stuff like turn your truck on and see if the alternator gets really hot or you can hear the bearings inside of it whining.. If you can take the alternator out and or take the truck in to an auto parts store would be the best for you if you don't have a voltmeter.. Another really simple test I've done since I was a kid was turn the truck on and take off the negative battery cable while it's running. If it dies then you know what your problem is. I wouldn't totally recommend that method since I've only done it on old vehicles but it's there if you want to use it