89 S-10 Blazer has Electrical Problems - NEED HELP!!!

Hello everybody, I'm a pretty smart guy when it comes to electronics, which can make me very dangerous. I have a problem with my 1989 Chevy S-10 Blazer that I need some help with. Here's the deal...
About 4 or 5 months ago, I started to notice that the battery wasn't holding a charge, and decided I needed to replace it. I was lazy, and didn't do so. Since this was our second car, we only drove it once a week or so, and when we did, we usually had to jump-start it. That worked fine. Last week, I finally decided it was time to replace the battery. I went and bought a new batter, pulled the old one out, and put the new battery in. I connected the new battery and expected to see the under-hood light to turn on... it didn't. That was weird. Well, let's see if it will start. Nothing. Not even a click.
After some diagnosis, I have found a few weird things. First, when I connect the battery properly, I get a perfect 12.56VDC when measuring at the positive (+) battery terminal and the engine block. This tells me that the block is properly gounded. Good. Then I tested at the "terminal block" and the engine block. Nothing. So instead of using the engine block as a ground, I actually put the probe on the negitive post of the battery. Nothing. Okay, so it looks like I'm not getting any positive flow to the "terminal block" located in the back of the engine compartment. I've tried to trace it back, but I haven't done a very good job. Okay, so something is obviously not working right, but what is it?
Okay, so here is where it gets strange (or at least I think it is strange). I decided to disconnect the negative (-) connection to the battery. Essentially, I have the positive side hooked up, and the negative is just hanging there. With this done, I would expect to not be able to get a voltage reading off of anything except for the two battery posts (since the car is no longer grounded). This was not the case. I put the negative probe from my multi-meter on the negative (-) post on the battery and touched the case of the alternator. My multi-meter (DMM) jumped up to 12.56VDC. What? Okay, let's try again. Put the ground probe into the negative post of the battery (but note again that the car frame itself is not grounded) and touched the engine block. DMM reads 12.56VDC. Okay, so now it looks as though my car has changed into a positive ground.
I can tell you where I think the positive flow is coming from... I just don't know if this is to be expected. I believe that the cable running from the positive (+) post on the battery to the post on the alternator is causing the housing of the alternator to be positively charged.
I don't really know what is going on, and like I said, I know just enough to cause some problems. Any help or insight into this issue would be GREATLY appreciated. I am looking to sell this car, and I really need to get it running.
Oh, and one last thing... I quickly mentioned it above, but when the battery is properly installed, absolutely NOTHING works in the car (from an electrical standpoint). Not even the dome light.
Thanks in advance for any help.
Sincerely, Scott Bauer
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Do you have "Peak Hold" turned on in the DVM?
As for no voltage when you connect the battery, do you have 12v at the starter solenoid to ground? Establishing ground is one thing, but you need to establish 12v too, as you well know. When you measure across the battery terminal and the engine block you are only making sure that the negative post of the battery is well connected to the engine ground - you are not verifying that the positive post is well connected to the car. Do you have two leads that are supposed to hook up to the + side of your battery? Are they both? Have you made sure that there is no corrosion built up inside the battery connectors? Have you made sure that both cable ends are well cleaned?
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scbauer wrote:

dealers. When the president or general manager told me how honest he was, that was a tip-off that he was a major crook.
Just load test the dam battery and make sure the connections are good. It is simple, even for a smart guy such as yourself.
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And use a test light. You can buy them for a buck or two. A DMM is too sensitive for what you're doing. Here is the big question: Did you hook the battery up backwards the first time? If you did you have an open fusible link.
Al
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In article

Fuse link.
You've blown a fuse link either during jump starting, during your battery swap or during your 'testing.'

Congratulations! You've discovered how to measure a voltage drop. Since your B- circuit is open, and you've substituted that circuit with your volt meter, you're reading the voltage differential between the engine ground (alt case) and the battery negative.

I bet you get the same reading no matter where you put the meter lead, alt case, engine block, chassis, etc.
Let''s do another voltage drop. Connect the battery as it should be. (+ and -) Put your positive (red) volt meter lead on the battery positive post. Put the negative (black) volt meter lead on the junction block (terminal block) on the firewall. Reads 12.56 volts doesn't it?

Blown fuse link. They're down where the big positive battery cable connects to the starter.

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