4.8is Question
 

I have been having some issues with the alternator on the 4.8is for some time. here is what happens. It started out that the X would sometimes go haywire, Engine Failsafe, limp mode, low tire, abs etc. Then I would shut off X and restart and X was good.....for weeks. Then I noticed I was getting warned that this would happen prior to actually happen. My Radar Detector would show 'Low Voltage" on its screen. i would shut X off and restart and it was good to go. Family member owns a repair shop and I was there one day when i started the X and the "Low Voltage" was on the Radar Detector. Kept it running and tested the Alternator. 11 Volts. Shut down restarted, 14.9 volts. Can this be something other than the alternator? Why would shutting the engine off and restarting fix the problem? Just dont want to waste the money on an alternator if this is not the cause.
Thanks for the help.

if you have a multimeter, the next time it does it, measure the A/C voltage coming out of the alternator, if you get any, its time for a rebuild/voltage regulator.

Sorry to sound dumb but is that different that what they already tested?

they are measuring the D/C voltage output.