More Alternator Blues

[gedmeyer]

I thought I had solved this problem a couple months ago, but apparently not "Bubba Alternator Wiring". In any case, the vette died on the road two nights ago with a dead battery. I could jump start it, but it would always die out after the battery lost charge. So the Alternator is not charging the system.

I went back today and fixed the wires so the alternator is hooked up exactly as called out in the Service Manual. All red wires at the alternator read the voltage of the battery (measured at the posts). With the car off, the brown wire reads 0. The brown wire reads 11.8V with the car running and with the ign on and the engine not running.

The generator warning lamp is illuminated. HOWEVER, when I rev the engine past 3500 rpm, the voltage gauge jumps to a little over 14V and the warning lamp goes out. But, a few seconds after the RPMS drop, the voltage drops back down to being low and the light comes back on.

I had Advance Auto Parts test the alternator this morning and they said it tested good. I kinda thought my symptoms meant a bad regulator, but they say the alt. is good. Any suggestions?

-gedmeyer

 

[Ludigdrums]

Here's a long thread with a similar situation... http://www.corvetteactioncenter.com/forums/showthread.php?p=399842#post399842

I think it is your alternator. I ripped through all my wires, even at the fuse panel, cleaning, making sure good connection.

Followed the service manual instructions for checking voltages and such, and it kept pointing me in the wrong directions.

It all turned out to be the alternator in the end.

Good luck!

 

[gedmeyer]

The shop manual says that the brown wire should be around 0.2 with the ign. on and the engine off. However, mine reads 11.8. Any suggestions?

-tim

 

[gedmeyer]

I *think* I solved the problem.

I had been running with the choke disconnected. Once I connected it back up, I got 0.0V on the brown wire (with ign on and engine off). As soon as I fired it up, the voltmeter went to just over 14 and the light went out.

So does the choke wire provide a ground for the circuit?

 

[Ludigdrums]

Well, in a way I guess. I didn't mention that one of my problems was that I had a relay that started to make a buzzing noise. It turned out to be the choke relay. Funny thing is, I have a Holley w/electric choke. That brown wire is somehow connected to that relay as well.

Like I said before, I went on such a wild goose chase doing exactly what you are now, measuring voltages and such...and in the end, it was the alternator...which, I had ruled out from the beginning tests I had done according to the manual.

Also, I don't think that the way auto stores test these alternators provide accurate results...for one, they really don't have a load on them, and I don't think that they can test the diode trio in these units.

I don't claim to be an expert on this topic, but I just don't want you to go through what I did for no reason. Although, it's good to know that all my electrical contacts are clean now.

Good luck! And if you want, give me a ring 516-857-2118...it might help to talk through some of this!

- Jeremy