I posted an issue on my Z/28 a while back and I just got the car out of storage this week so I started checking out the electrical system today. My first task was to check the voltage output of my alternator. While I was looking for how I was going to check this out, I noticed a broken wire coming out of my alternator. Geesh... imagine that. The wire was the yellow wire that comes out of the plug in the back of the alternator (two wires total...1 black and one yellow) Well, I fixed this first and got it all hooked back up and started the car and got it idling at about 900 RPMs Voltmeter was reading 14.07 volts at the alternator and 13.87 at the battery.

This did not seem to be bad to me. I would expect a little voltage drop and .2volts did not seem excessive. I think my mistake was fixing the yellow wire before I did the test. I should have done a before and after check. Two questions come to mine:

1. Does the voltage seem normal or at least normal enough to not think I need to go to a larger battery cable??

2. What does that yellow wire go to? and could this have been a contributor to my electrical problems?

I charged up that battery that was dead at the end of last year and it seems to be working fine for now. I am hoping the yellow wire was a symptom that I fixed with a wire stripper and a new spade connector. Any such luck??

Thanks,

Robert (a.k.a.Mytmouse)


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My 67 SS396 Chevelle (http://www.pascale.org/Muscle_Cars/Mytmouse/mytmouse.html)
My 70 SS396 Chevelle (http://www.pascale.org/Muscle_Cars/Myt_70/myt_70.html)
My 68 RSZ/28 (http://www.pascale.org/Muscle_Cars/Myts_Mouse/myts_mouse.html)

Robert Stacho (a.k.a Mytmouse on Team Chevelle)

I will be the first to tell you that I do not have a schematic of your 68, so I can't tell you what the yellow wire for sure went to. But, it's likely (no...it's certain) that it went to the regulator which controls the alternator's ability to charge and provide current for the entire working system. So, it is likely that the system was degradated in some way....but I would have thought that you would of had a "gen" light indication on your dashboard!

The way to test you complete system to see if it sustains enough charging current is to test under a large load. Voltage testing itself just tells you what the current conditions are under the presented load.

To do this test...first of all it's imparitive that you know that 12.65VDC is a fully charged battery. Some voltmeters might read a little different than that due to accuracy. Start car, turn every accessory on known to man....lights, air, open doors, radio, etc. Now, go and look at your voltage at the battery terminal. That reading should be in the above 12.9 range to be sustaining any charge at all. If it is dipping below the preverbial full charge level, then it is discharging and depending on whether or not you have added accessories to your car, the wiring might be the culprit or a larger alt.

Measure the voltage output out of the regulator (big wire #10) terminal...that should be red. If that wire is significantly higher in readings...then wiring maybe at play here......including grounds.

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STEVE JACK
ConceptOne Pulleys and Brackets
Techical forum/links at www.inccn.net/techforum.htm (http://www.inccn.net/techforum.htm)

I believe that yellow is the lead that kick starts the alt's charging process. When you turn the key in the ignition and start the car the lead gets voltage applied to it. Without the kick start so to speak the alt will spin all day and not output. I learned all about this 200+ miles from home at Hot Aug Night last year. On my '69 the wires are white and blue

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...Dennis
"The '69 (http://chevelles.com/showroom/fine69_03.jpg), the '96 (http://chevelles.com/showroom/fine69_02.jpg) & the club (http://camaroslimited.com/)"

Actually I think that wire is a white that may have discolored over time and now looks like a faged yellow wire... No idiot light on but the electrical meter (-40.....+40) in my factory gage package still doesn't work. I was kind of hoping that was part of that problem. The car ran fine but I didn't know whether it was discharging the battery because the meter wasn't working. I should say it ran fine with a fully charged battery. I remember when the battery was dead or dying I had a hell of a time keeping it running and my electric windows barely worked. Start ing to sound like that wire may have affected my charging system and as long as I left on my short cruizes with a full charge...everything was OK. I think I will do some more testing under load and then see how things work out befor I start putting in a larger cable.

Sorry to hear about you problem that night Dennis...but I guess we come to expect a little tempermentalness with these theings...after alll they are 30+ years old

Thanks for the help

Robert

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My 67 SS396 Chevelle (http://www.pascale.org/Muscle_Cars/Mytmouse/mytmouse.html)
My 70 SS396 Chevelle (http://www.pascale.org/Muscle_Cars/Myt_70/myt_70.html)
My 68 RSZ/28 (http://www.pascale.org/Muscle_Cars/Myts_Mouse/myts_mouse.html)

Robert Stacho (a.k.a Mytmouse on Team Chevelle)

If your ammeter is not working...then the problem can be there too. The charging current all comes thru the meter to the battery and load. There is a shutwire in these that carry the load. I would fix it too.

You are right about the yellow wire...it's probably white and goes to the regulator.

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STEVE JACK
ConceptOne Pulleys and Brackets
Techical forum/links at www.inccn.net/techforum.htm (http://www.inccn.net/techforum.htm)