first of all let me start off by saying that i think i have a short somewhere. i used a light tester and i tested each fuse, but i tested with the fuses on. now the right side of the fuse box which i think shows radio etc. the light never came on. i tested the left side, which shows hzd, pwr windows, int lights, etc. the light came on for each fuse. so thats light on all the left side of the box and no light on the right side. now my battery was weak when i did this so i got it charged up, still did the same, but now my automatic windows dont roll down. my volt meter shows a 11 and a 9-10 with the lights on. the headlights look bright and so does the highbeam. so i put in a new alternator because it has warranty and thats the 3rd one in 4 months. i took the car to autozone and they checked the battery as good but low and its an interstate 35hd 3 yrs old, but barely used. then the alternator, no charge came out. so now im puzzled as what it could be. could i have another bad alt?

 

Jeeezus, where to start...
OK, first off, you need a voltmeter. check the voltage at the battery engine off, then engine running. Off it should be about 12v, engine on it should be ~13.5 to 13.8 or so.
There are several things to check if the voltage engine running is low: connections and voltades on the alternator to start. Does the ALT light come on when you turn the key on?
Next, checking fuses with a light: if you have a light on one end of the fuse, you should also have a light at the other end.

 

when i took it to autozone. the battery tested 12v off and 10v on. as far as the gen light nothing comes on so i guess its not connected?

 

Good Luck Sixfooter.

 

If you have a power drop when you turn the car on, your alternator is clearly either bad or hooked up wrong. Check your belts, make sure it is spinning. Also, alternators will not generate any power when not attached. Its possible you fried the regulator on it, that happens quite frequently, if there are any bad connections/ shorts between the alt and the battery.
12v is like.. bare minimum charge for the battery. Typical voltages are between 12.5 and 13.5 volts off, 13-15v on.

I would never go by lights, either. So unreliable and imprecise.
Go to a battery place and have them test your alternator.

 

In general the left side of the fuse box is hot all the time , the right side is hot only when the key is ON.
Your alternator problem is more than likely a wiring problem with the car,not another bad alternator.
IMO Light testing fuses and circuits (including alternator) is fine. I use a light 98% of the time.
Alternator voltage testing you need a voltmeter.

If during light testing one side of fuse is hot and the other side is not hot the fuse is blown(bad). Also when testing fuses test the contacts that the fuse snaps into,a dirty or corroded connection there can fool you.

 

10v at the battery with the engine says the alternator is NOT charging and that the battery is weak, possibly just needs a good charge and maybe its bad. First things first:
There are 3 connections on the alternator: Battery (big red wire), Brown wire from the Gen light and a smaller red wire from the fuse link on the starter.
The Big red wire is the output that charges the battery and powers everything in the car. The smaller red wire, pin 2 on the side of the alternator is a voltage sensing wire that tells the internal regulator ouw much voltage to put out and the brown wire is a Field Exciter signal that comes from the Gen Light. You must have voltage from the Gen light wire or the alternator will not charge. You stated that the Gen light does not come on so lets start there, Disconnect the connector from the side of the alt and ground the brown wire, the Gen light should come on bright with the key on. If it does not, check the bulb and the Gauge Fuse. If the light Does come on then that part is ok. Now the small red wire, it supplies voltage sensing and it powers the underhood light. With the connector off the alternator, check for battery voltage on the small red wire, if its there your good there also, is it is not there, check the fuse link, its a smaller piece of wire spliced in line and connected to the big battery cable on the starter..
Lastly the Big Red wire on the alternator output terminal goes to the battery for charging, follow it all the way thru, it may have a bad splice somewhere, maybe right under the battery box, thats a common place..
One more check is the alternator ground, it should get a ground thru the case, there is usually a black wire on the mount brracket under the alternator.
See where all that gets you.
Here is a schematic for an 81, but they are pretty much the same.

 

ok. seems that when i bought the car whoever installed the alt put the harness plug reversed so i naturally followed the way it was connected when iu replaced the others. i decided to reverse it and now i have a 13v reading.

 

thanks to everyone for their help! my car is charging properly and i got my windows to work. now i gotta tackle this short. gonna buy a battery disconnect post in the meantime. this site is awesome!

 

Ta Daaa...!