Complete power shortage

Your test method is not something I can follow. Resistance readings must only be taken in circuits that are not connected to the battery or power source. Voltage readings are almost always taken with the black negative probe on the negative post of the battery, or a paint-free point on the body or engine. You might learn a valuable clue with the way you are doing it, but I cannot determine where to send you next.

Instead, based on your thorough description of the symptoms, (thank you), follow the smaller positive battery wire from the battery post to the under-hood fuse box. Be sure that connection is clean and tight. That is by far the biggest cause of this problem.

Also follow the smaller negative battery wire to the body and be sure that connection is not rusty. If that does not solve this, I will dig out a wiring diagram and figure where to start testing.

The clinker here is it took a while for that huge fuse to blow. That fuse is going to blow if the wrench contacts the large output terminal on the back of the generator and a metal part on the engine at the same time, AND only if the battery is not disconnected. To blow at a later time, it is always possible something was assembled incorrectly inside the generator, or a part is failing, but that is not common. More likely, I would start by looking at that terminal to see if it is close to touching a metal part and engine vibration is causing it to touch intermittently.

Something uncommon to consider is most cars are available with more than one generator. If yours came with a smaller, (electrically), generator, the appropriate fuse would have been installed. Most of the time a larger generator is the same physical size and bolts right onto the engine. It will work just fine except for those very rare occasions when it needs to develop its maximum output current. That is when that current might exceed the fuse's rating. Typically this only happens when performing a "full-load output current" test, but the mechanic would catch that.

It costs the manufacturer more to initially install the bigger generator on millions of cars, so they use the smallest one that will do the job. When it comes to rebuilding used generators, it costs that company the same amount of time and parts regardless which size they're rebuilding, so they like to just rebuild the bigger ones so more applications are covered. That means it is possible to get a bigger replacement generator than you had.

Under all driving conditions the generator will only develop exactly as much current as the car's electrical system needs. A bigger generator will not develop more current than a smaller one. It simply has a bigger capacity to develop more current. For that reason, if you should find you do have a larger generator, you can be safe in installing a larger fuse without worrying about the size of the output wire.

You might also want to follow that wire from the fuse to the back of the generator to see if it is bare or pinched anywhere.

Hey Justus,

I know this sounds kind of simple but I have seen where the battery will short out internally and cause the problem you have described. The car will not even jump, how old is the battery?

Best, Ken

You da man! Nice work.

Please use 2CarPros anytime, we are here to help and tell a friend.

Best, Ken