Hello again! New Problem with the VoVo...The old alternator had stopped charging properly, so I replaced it. The very day I put the new one in, I noticed that the oil pressure light started coming on intermittently, but the alternator was working, and the oil was fine. That was probably two months ago. Now, the alternator has been getting worse, to the point that it now cannot charge at all. I realized my mistake was that I had hooked the oil pressure sensor wire to the alternator ground, so the alternator was sending power to the light, I guess. Now I have taken it off, but am unsure of where the actual ground wire is, as I don't see any other wires in the vicinity. I made a short lead and connected it from the alternator to the engine block, but the alternator still soesn't work. Also, when I have the ignition in Position II (engine not running), no instrument lights come on. They are not blown, but simply don't come on like they used to. Any ideas what might be the issue? I don't have a voltmeter, by the way. Thank you! And the car can be jumped to start it, but it doesn't charge on its own, so it just dies after a short period.

 

So I have replaced the exciter wire, which fixed the issue with the instrument warning lights not coming on when the key is at position II, and ran a short lead of 12ga wire from the alternator ground connector to the body of the car, but the battery still will not hold a charge. I was attempting to jump the car battery off of our motorhome, and it was obviously getting some juice (because the car battery was completely dead) but still not quite enough amps to actually start. Could it be that I used too small of a ground wire? Or does it perhaps need to be directly attached to the engine block? The old ground wire is much larger, shorter, and connects directly to the block. I didn't use the old connection due to access to the bolt, and I don't have any wire that large on hand. I do have some pretty hefty solid copper wire, but it is completely uninsulated....

 

ground wires don't need to be insulated.

that said, put the battery on a charger overnight, and charge it at a 10-15A rate. when its fully charged, disconnect the charger, wait an hour or so, and use a volt meter on the battery, you should see ideally about 12.6V if the battery is at 68F. less if its colder. note the voltage you read, start the car, and read the voltage again once things are a little warmed up, it should be about 1.2V higher, like 13.8V or whatever. if it is, your alternator is working. if not, you still have a charging problem.

that ground wire has to be able to easily handle the full 100 amps from your alternator. skinny wire will melt down like a fuse.

 

Well, I just had the alternator tested, and it passed with flying colors, unfortunately, because I'm now back to square one, or at least square three. When I put my little tester on the positive contact and the ground screw of the alternator, I am getting voltage from the battery, but it doesn't seem to be going the other way. SO if the alternator is producing voltage, its not getting to either the battery or the rest of the electrical system. Where could it be getting stopped? The battery light bulb is not burned out. The exciter wire has continuity. I replaced all of the battery connectors. Fuse 13 is good. What could it be? Sucks because we really need groceries, and the grocery store is too far to walk to (12 miles away) carrying two kiddos.

 

was that alternator test in the car, or was that dragging it into some bigbox store where they slap it on some mystery machine?

 

It was the latter...O'Reilly's, specifically, since that's where I got the alternator from in the first place.

 

ok, get a volt meter, and do the test I described above. that is the charging system test that matters, tests that it is or isn't working in the car.

if you dont see the 1.2V or so rise in voltage when the engine is running, then, engine off, ignition on, and verify that the alternator/battery light is lit (along with all the others), and measure the voltage at the D+ terminal (thats the smaller wire) on the back of the alternator relative to ground, that should be basically battery voltage. the B+ terminal should also be battery voltage with the ignition off or on.

now start the car, and measure the battery voltage, - to +, again, if its not 1.2V higher than the battery was when the car was off, put the - lead on the alternator body or ground and the + lead on the battery +. see that +1.2V delta? no? try the B+ terminal to the alternator ground? that should DEFINATELY be 1.2V higher than the 'off' battery volts.

this is why I really dont like those big box store alternator tests (or really much of anything else). any auto electric specialist would have done this without even being asked.