My tahoe is completely dead the battery and alternator tested good. prior to it dying the lights and the a/c would occasionally glitch out.

Most likely a bad alternator..batt isnt gittn chargd. The diode is bad causing the alt to suck juice from batt. Also the main wire from battery to back of alternator I wud test first for wear. A bad one impedes chargn

Sounds like you may have a dead battery or alternator. Disconnect your battery and take it to your local auto parts store and they will test it for you. You can do the same thing with the alternator. But call ahead to find a store that is capable of checking these parts for you. A check you could do yourself is jump start your battery off another car or charge it on a charger. If it turns over and starts, let it run. If it dies and the same thing happens with the ticking. Chances are you have a bad alternator that's not charging the battery. So the vehicle ran off of the battery til the battery ran out of juice. If it keeps running but won't start back up when you shut it off, chances are good your battery is bad and the vehicle is running off your alternator.

Diagnose the door lock issues first,that you know is a problem

Why would you replace the alternator ?

If the light is on when car is running, the alternator is still not working. Check your power distribution center near the battery for any fuses out. Maybe there is an alternator fuse.
Is your battery good? A completely dead battery may not take a charge from the alternator. It needs to be charged off the car. Have it load tested at a parts store to see if it's good.
Is your alternator belt tight? A loose belt won't let the alternator work to capacity.

A ford needs a fully charged battery to work the alternator. You may burn out the replacement alternator by hooking it up to a dead battery. Get the battery charged and have it load tested. You may have a bad battery and it should be checked. http://www.cardone.com/english/club/select/electrical/protech/tech_bulletins/PT37-0006.pdf

Hello,
When you say battery voltage how are you testing it? Are you looking at a gauge on the dash? Or are you physically testing it with a multi meter? If the truck is dying and you recently replaced the alternator and battery I would first suggest you to check all them connections again real good. Snug them all up. Check for corrosion and clean as needed. Did you replace the battery and alternator with new/re-manufactured battery and alternator? The alternator needs to put out at least 13.6 volts to charge your 12 volt battery or the battery will not maintain a charge. However the alternator runs the vehicle once it is started. The battery is used only to start the car and then the alternator runs it. So if your vehicle starts and runs and then dies you may have a bad alternator. Check your connections first and then test the alternator with a multi meter. Anything less than 13.6 volt will not suffice. 14+ volts would be the hopeful output of a good alternator.
regards, Tony

I think you have an intermittent electrical condition somewhere in ignition/start/run circuits.

I suggest you pull the battery and alternator then take them to a auto parts store for testing. Most major chain stores will do this for free. Another alternative is to get the car running with a jump or battery swap. After you get the car running remove the positve (red) battery cable. If the engine dies the alternator is not working. If the alternator is bad you will want to get your battery checked. The alternator going out could have damaged the battery so that it will not hold a full charge. Good Luck!

you might have the alternator checked or simply replace it.. i would also replace the battery if its more than 2 years old

bad battery module for the light or a dieing cell in battery

batterys can be tested and wont show a dead cell at all but you will be told that the battery good
most batterys are refurbished batterys sometimes getting the luck of a good battery is 50/50 chance

heres a way to test the battery and alternator at the same time
start vehicle
disconnect battery positive post
if vehicle dies the alternator is at fault if vehicle doesnt die its the batterys life dead cell