There is an issue with my Blazer that has gotten worse since I got it. When I rev the engine above idol all my lights(interior and exterior) flicker repetitive and constant, and the voltmeter fluctuates rapidly. It's not that big a deal, more annoying than anything(cause i did get pulled over once because of it). I thought maybe it has something to do with my alternator going bad or a voltage regulator. I took a video of my interior lights.. the quality got crappy when I uploaded it, but at the end of the video you can see it pretty good on the instrument panel. If anyone has seen this before, i could use some help diagnosing and fixing this problem, thanks.
http://www.youtube.com/watch?v=GYUmDamGsLE

 

do you have a multimeter? see what the volts are? my fullsized kinda did something like this but everything just went bright and it pegged the volt gauge. voltage regulator took a crap

 

5 bucks says it took a crapper like the one in my '98 did last year.

mine was doing the samething while on the highway (where i first noticed it). get your alt tested, or grab a DMM and check it out yourself.

 

i have the same problem. my voltage goes all the way up to the red and then the truck turns off after like 10 seconds.

 

Alternators produce "alternating" current, AC (as opposed to "direct" current, DC)... the voltage is something on the order of 70-150V depending on the speed the alternator is being turned.

The voltage regulator is what lowers (regulates) the voltage from that 70~150V down to 13~14V.

The rectifier/diodes are what convert AC to DC, they do this by only letting the current flow in one direction.

As far as I know on our vehicles everything is built into a single device called the alternator, no separate regulator like on older fords.

Either way it looks like you've got a failure with the unit, probably some bad diodes or maybe the brushes on the alternator itself. You can do a lot of expensive electrical damage by leaving it like that or waiting for it to get worse. Computers, radios, etc are all potentially damaged. Bulbs might start to burn out if the voltage is getting too high on the swings.

A new lifetime warranty alternator from Autozone is $115, plus tax...

It took me 23 minutes to replace the alternator in their parking lot yesterday morning (started my Blazer to go to work, the battery light was on, voltage read 11.6V, i.e. no output from alternator).

You need these tools:
13MM socket for the alternator mounting bolts (3 bolts total)
13MM wrench to hold the output stud (maybe not, my replacement was fixed)
5/16" socket to remove the negative battery cable
1/2" breaker bar for the belt tensioner (of if you're not a *****, you can do it by hand)

Make sure you disconnect the negative cable of the battery first!!!! Also, before you start anything, buy the new one, then hold it next to the old one and make sure it looks exactly the same--all the mounting bolts are in the same place, same distances, configurations, etc. AZ had two different models that were slightly different, a 100A and a 105A... I chose the 105A first and it happened to be the right one... maybe the 100A would have fit too, but I don't know. It was a $5-10 difference, so I went w/ the slightly higher amperage version.

I'd also rec. some electrical contact goop for the output stud and the molded connector on the alternator, as well as some anti-seize for the three bolts you'll remove.

Seriously tho, if it takes you more then 40 minutes to do this job then you must have been playing with yourself for at least 15. I barely got my hands dirty doing the job.

Good luck