My gen light stays on on the dash. I've done the quick test for the alternator and regulator. It says the alternator is faulty and I've done a regulator check which says in the book if the difference in voltage of up to 0.5 volts is found the regulator is faulty and I'm getting up to 7's and 8's volts difference. which says the regulator is faulty as well. I put a new regulator on and it made no difference. I want to go for a 6 hour ride, do you think I should cancel the ride because of this problem?

NO ENGINE TOLD ! 2.0 OR 2.5LITER?????????
TH 8TH DIGIT OF YOUR VIN TELLS YOU WHICH ENGINE IS THERE, PLEASE TELL THAT FIRST.
The alternator is overcharging. what makes you think so?
a meter test.?
scan tool shows DTC that said that>?
OK JUST FLICKER,
lights flicker, what light, heads, or charge lamp error
or what? (i guess all)
putting in 3 wrong alternators is painful , there are 2 used, here. on 2 engines
one is pcm controls, other is not.
The 2 engines and matching ALTs:

DURATEC -VE 2.5LITER ONLY

ZETEC-VCT 2.0L ONLY

THEY ARE NOT THE SAME. ALT ! NOR ENGINES

DURA HAS 3 FUSES TO BLOW. BOTH ALTS USE THESE FUSES
F30-CJB. 7.5a, CENTERAL JUNCTION BOX.
and F2 =BJB, 15AMP BATTERY JUNC. BOX BJB
AND FB 175 AMP
THE REG IS INSIDE THE ALT HERE, NOT PCM

DID YOU REPLACE THE ALT WITH THE NEG LUG ATTACHED, IF YES, THE 175AMP FUSE IS BLOWN BOOM

ZETEC USES PCM REGULATION

AND SAME 3 FUSES TO FAIL, 1,2,3..

THE 175 FUSE MUST BE GOOD. TOO.

THE CORRECT GENERATOR FOR YOU ENGINE MUST BE USED
THE DURA and zetec alternator gens can NOT be mixed up here ever!

best way to buy any alt is by VIN # code or fail 1/2 the time or even 3times in row. or 175amp is blown
if buying over the counter (a new alt) tell them there 2 kinds used in 2000, tell them the vin 8th code.

voltage gauges read the out put voltage from a alternator
it should be a max of 14.5 to 14.8 volts
if it is higher then the alternator or regulator is faulty and needs removing for a bench test or replacement
there may be a connection to the dash light through the light control module that controls the voltage to those lights
fix one and see it that fixes the second.

This sounds more like a faulty alternator. Sometimes an alternator can still produce adequate voltage and amperage to keep everything running, but they are governed by a voltage regulator. If the regulator goes bad, the alternator may have little of no output, or it will not limit itself properly causing gauge problems, and various light on the dash to not work or sporadically come on.
I'd take the vehicle to have the alternator tested at least.
Don't settle for one of the part store tests, they won't give you all the information you will need. A properly working alternator should charge anywhere between 13-14.6 volts and depending on the vehicle 90-150 amps.
I hope this helps in some way

Brother Mark, changing the battery with a new one being done won't make the light go out, as you noticed. Light is still on so you changed the alternator. Good, but the battery light is STILL on. This only means that the charging circuit from the alternator is not working in the voltage regulator or the wiring is not connected properly to the alternator/regulator. A new battery will show over 13 to 13.5 volts not connected. An old battery will still show 12 volts and still be weak or bad. After connected and engine running, the system will show at least 14 volts because alternator/regulator is working properly, using a voltmeter/load tester connected to the battery. If after replacing the battery and alternator it is still reading 12 to 13.5 volts, it is not working and the light will stay lit on the dash. You may have purchased a faulty alternator if the system tests out this way. Have your system checked with a volt meter or load tester bit be sure all the connections are proper and clean.

To remove the lead from the battery to the alternator while it is running is to invite a destroyed alternator . Varying voltages with engine RPM is indicative of a bad battery or problem alternator regulator . Have a load test done on the battery to check for cell problems and have the alternator bench tested to check the performance .

Low battery charge, Battery Defective(Could have a bad cell), Loose or missing alternator drive belt, Faulty Alternator, Open or short system voltage circuit

check for faulty ground wire both chasis ground and engine ground for damage looseness and corrosion

When was the alternator replaced? was it a remanufactured alternator? This is common on GM trucks, fluctuating voltage is caused by a faulty alternator voltage regulator. Have the alternator tested, strong possiblityits defective!!Hopefully this helps!!

sounds like the voltage regulator