Yes,that is what is driving me crazy. With the battery to a small ground spot I measured 12.5 volts. With positive to negative post I'm reading 12.5 volts.

 

see what you are not understanding the amount of connection you need to show you have 12 volts can be delivered thru something as small as a common desk staple, but would not stand a chance of doing much more. hence you have cables the size of a finger with connections that could be removed with a lug wrench.

have you checked the connection at the starter? and if you do Disconnect the battery

 

Okay, the battery might be good. However, you said even the autoparts store had an issue hooking up the negative to do the test. There could be a problem inside the battery terminal, maybe it is cross threaded? I might see if you can get then to exchange it for a new one and see what that does.

I don't know that chasing fuses will answer anything, if I'm not mistaken, a fuse is either work or fail, not really capable of intermittant failure? Maybe I'm wrong, but I've never seen it.

The car going completely dark is the key here. You are losing a connection somewhere in the direct power line. Those 12.5 volts are not going anywhere. There could very well be a break or a short in the main battery cables, either pos or neg as well.

 

Your train of thought was similar to mine. The only problem is now that it is not showing power, I can't do anything to get it back on. When it would happen before, I used to be able to wiggle the ground a little and get it back in action. It wouldn't stay good for long; sometimes after a drive it would not have power upon trying to start it again. Under power, the car ran off the alternator, so it really sounds like something is intermittent and upon hitting bumps, it's getting "undone".

Here's my update. I put a brand new battery in the car this morning. I didn't hear the headlight motors but the dome lights went on and the car started right up. When running, I was seeing around 14 volts(alternator must be working).

I drove it around the block about 300 yards and over a few speed bumps and dips at about 15 mph and came back to the house. After letting it sit for a minute, I went to see if I still had power. I had nothing. I tried moving the ground and I still have nothing.

During the drive, I noticed that the car started missing a little. It still drove but didn't sound 100%, like it was running on 6 or 7 cylinders.
When I free rev'ed it, it sounded okay but at part throttle driving, it did not. I've never experienced this except for the past two times I drove the car.

Now for measurements.

Power across the lugs of the battery, 12.5 volts. Power from the distribution block behind the battery, 3.4 volts! I checked twice to verify. Isn't that thing supposed to be hot all the time? What can I check in sequence for bad connections? When looking at my Haynes manual, there is a chart that says that the battery goes to the alternator and the starter, but where else, if anywhere does it go? What should I check?

 

I just went out to my 93 and put a volt meter on the power junction behind the battery and I got a solid 12 volts, so a would look at the wire that goes from battery to fuse box make sure all looks good No corrosion around fuses, then follow wire from fuse box to behind battery junction, if yours is routed like mine I see potential places there could be a rub thru short.

 

well, took off the positive cable and cleaned the corrosion off the positive terminal with baking soda, water and a tooth brush. I reconnected everything afterward and made sure everything was snug and nothing.

So, off to the next step in the chain. After leaving the battery, it looks like it goes to the starter. Is that correct? I've got the passenger side of the car up in the air, so hopefully that'll help.

 

I am pretty sure it does but before you go near the starter DISCONNECT BATTERY even though you are chasing poor connection you have pretty much done all of what should be done getting their and would hate to see you go and make a big arch accidentally make a path to ground.

 

Well, took the car around the block again. Voltage was at 14 at the start and 11.7 by the end. It's time to replace my alternator to fix what I broke. I'm going to try to pick one up tomorrow.

I did the exact same drive as last weekend and the car started again once I got home.

Prior to leaving, I measured 12.4 volts at the distribution block behind the battery prior to the drive. I also measured 12.4 at the alternator lug.

So, I'm kind of dead in the water until I can get the situation to happen again and measure various places for voltage. If it does happen, any additional places that I might want to measure for voltage?

 

update.

I installed the new alternator today which was super easy. The car now reads 14.3 volts off the dash at idle. The alternator was off a 1996 and was with very low mileage.

A quick question; if the fusable link to the jumper block behind the battery is going bad, would it cause a no power situation similar to what I'm experiencing?

I'm going to go buy a $3 fusible link and add another wire to my positive post and see if it fixes the condition. I already have a second nut on there for the stereo system so it'll be added there. Hopefully that will do it on the electrical side.