Headlights flicker on and off at times .interior dash lights get dim and bright. checked alternator and thats fine.

have a load test done on the battery to check for internal faults
it may be a problem alternator , loose leads and connections or problem regulator
could also be a faulty /loose drive belt

Normally when headlight flash its and overcharge problem max volt from the alt is 14.5 video is if you got to change your alternato

Short circuit near the rear hatch.

you need to run another cable to frame of car or fix existing one you have a bad ground to chassis

you forgot, does it do that running engine or not.?
ok the main battery is car is doing that.
use a voltmeter, at the battery or even at the CIG lighter port.
12.6v DC, not running. rested. running voltage is 13.3v to 15vdc,

start engine, is rpm above 800 RPM at all times, or more?
if not, the alternator will be too slow, and drop out and when that happens , the lamps will dim. (a 3 volt drop does that)
1: all fuses good
2: battery term lugs clean, not green
3: fan belt to alternator not loose. slipping.
4: charge lamp on dash not ON, running.
5: check engine lamp not on, running (if yes,scan it now)
6: test the battery , batteries are LOW life objects, (die-easy-not-hard)
test the battery , using a load tester or take it in for testing, it's free.
or try a spare battery from another car. do not reverse POLARITY.
this gets the lions share.

First, check that the battery connections are clean and not corroded. If not look for the ground wires that connect to the chassis. Check to see if any are corroded or loose. Finally if that has no effect, you have a short somewhere in your wiring. The easy way to isolate it is to pull the fuses for each device one by one and see if the dimming stops. The last one to cause the dimming is the problem. If it happens when you hit a bump it also might be a ground fault in the interior car grounds....good luck!

take a test light and check your fuses , make sure both sides of the fuse is hot ! check power at alternator if no power gos in no power will come out.

My guess would be a failing alternator. Get a second opinion on it.

we had the same problem there is a small line that connects itno the alternator, it kept jiggling loose. we found a way to tighten it and the problem went away

Definately an electrical problem....first off, check the battery and alternator connections to make sure they are tight. The problem has to be before the fuse box because the headlights and interior lights are on different fuses. It sounds to me like a loose wire, corroded battery terminals, or an alternator that is going bad. An alternator is a relatively easy and cheap fix. They cost about $100 and require removing a few wires, 3 bolts, and the serpentine belt.