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Discussion Starter · #1 ·
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 loking for how I was going to check this out, I notice 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 dis 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,

Mytmouse




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My 67 SS396
My 70 SS396
My 68 RSZ/28
Mytmouse A.K.A. Robert Stacho
ACES Member # 04359
 

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Mytmouse


1- If you have 13.87 V at the batt @ 900 rpm your alternator is probably fine. You can try this- (run at about 1500 rpm for a few minutes to fully charge the battery) with the headlights on bright and the blower on high speed, run the engine at about 1500 rpm. If you have 14 + volts at the batt your in good shape. If less than 13.5 you should rebuild or have the alternator rebuilt. A bad battery will also cause a low reading but if the amp gauge is working it will indicate charging much of the time. A good battery will only charge for a few minutes after starting.

2- The yellow wire- Assuming you still have the external voltage regulator and that it’s the wire connected to the R terminal of the alternator. Typically the wire colors are white to the R terminal and dark blue to the F terminal. White could have easily turned yellow over the years. Anyway the wire connects to the field relay of the voltage regulator. Basically it turns off the idiot light. The charging system will function with it disconnected.

You may want to check with your local law enforcement as I think it’s illegal to own three extra nice muscle cars. Turn yourself in!

If it’s not illegal IT SHOULD BE.


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Discussion Starter · #3 ·
Good one Elree...made me smile.

Yeah it could be white and yellowed over time....it actuallly looked like a very pale yellow.

Thanks for the information

Mytmouse

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My 67 SS396
My 70 SS396
My 68 RSZ/28
Mytmouse A.K.A. Robert Stacho
ACES Member # 04359
 
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