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 Alternator on B7 Chevy
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bwest
Administrator

United States
2319 Posts

Posted - 10/31/2013 :  07:40:16 AM  Show Profile  Reply with Quote
Well, normally an alternator is an easy fix but this one is really eating my lunch. I have an old B7 (2001) with the delco alternator on it. This is the same unit I just rebuilt the engine on. Anyway, the volt meter on the dash was registering high so I checked it with a meter. I got 17 volts. Swapped the alternator out with one I had rebuilt and on the shelf. This one registers 15 volts. Took this one off and took both to the alternator shop and he couldn't find anything wrong with them but went ahead and replace the regulators in them. Brought them back home and there is no change. Someone recommended checking the grounds such as battery to frame, frame to engine, engine to alternator. All seem to be good and I even took a jumper cable and went from the battery to the alternator. Still no change.
Any ideas?

torque
Senior Member

Canada
71 Posts

Posted - 10/31/2013 :  5:52:52 PM  Show Profile  Reply with Quote
With your jumper, did you check both positive and ground directly from the battery to the alternator? I can't remember this wiring off hand, do you have just the positive and ground on the alternator, or do you have a third smaller wire? If so, try a jumper right from the battery to the smaller wire. If it is overcharging, the regulator is not sensing true system voltage, you have a bad connection somewhere, just to pinpoint it.
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bwest
Administrator

United States
2319 Posts

Posted - 11/01/2013 :  08:59:25 AM  Show Profile  Reply with Quote
Thanks torque, I think it has to be not sensing the voltage. I have main (larger) positive wire, the ground, a smaller wire connected to the "R" terminal, and then the two wire connector. So, is it the red wire on the two wire connector that "senses" the voltage? I think the "R" terminal is for the tach somehow.

Bryan
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torque
Senior Member

Canada
71 Posts

Posted - 11/01/2013 :  4:29:07 PM  Show Profile  Reply with Quote
Looking at the back of the alternator, terminal 2, the one on the right is the sensing wire. You can run a short jumper to the Bat terminal on the alternator.
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bwest
Administrator

United States
2319 Posts

Posted - 11/05/2013 :  2:16:56 PM  Show Profile  Reply with Quote
Well, I've done it again! I did something a few months ago that came back to bite me! Thanks torque for your information. I had trouble with the two wire connector at some point before I rebuilt the engine on this unit and I inadvertently hooked the wires up backward when I replaced the plug. Sometimes I wonder if I am all here. lol I guess when you run a one horse show I have no one to blame but myself.

Bryan
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Southsider
New Member

4 Posts

Posted - 11/06/2013 :  05:41:30 AM  Show Profile  Visit Southsider's Homepage  Reply with Quote
In my other world (Ag mechanics) this is a common problem. Both the overcharging and the forgetting. The way I remember which little wire goes where is "It's 2 hot"
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bwest
Administrator

United States
2319 Posts

Posted - 11/06/2013 :  05:43:48 AM  Show Profile  Reply with Quote
LOL, I know what you mean. Good tip. Oh, I guess it's not too bad I just hate that I had to chase my tail on something so simple. lol

Bryan
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torque
Senior Member

Canada
71 Posts

Posted - 11/27/2013 :  6:00:16 PM  Show Profile  Reply with Quote
I am not glad it happens to you, but I am glad it doesn't just happen to me :)I help others all day solve complex problems, plan attacks on problems in a systematic approach........ then I overlook the simplest of things while doing my own troubleshooting. My latest, spent an hour ripping a heater assembly apart because I failed to take 2 seconds to look at the leaking hose going into it. 10 minute fix turned into an hour plus. Some days it is nice to go for a drive LOL
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bwest
Administrator

United States
2319 Posts

Posted - 12/02/2013 :  05:38:25 AM  Show Profile  Reply with Quote
torque, it's too bad that we don't have a like button on here. I'm with you, brother! I just wish it didn't happen when I'm in a pinch. lol

Bryan
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BJ Henderson
Advanced Member

USA
227 Posts

Posted - 12/02/2013 :  10:38:40 AM  Show Profile  Send BJ Henderson an AOL message  Reply with Quote
bwest, as someone else posted, it happens to all of us, brother!

The main thing is, you found the problem no matter how it got there, corrected it, and didn't lie to yourself!

CMTT,CMAT,CMBT
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