Alternator wiring rumors and confusion

[Guest tony78_280z]

If plug 2 on my alternator is wired strait to the battery does it continue to "run" the alternator (even if key is off) and thus burning out the alternator prematurely.?

 

Should plug 2 be wired to a switch? ignition switch?

 

I'm getting so many conflicting "stories" about the wiring of the alternator that I don't know what to do. All my research has lead me to believe that plug 2 simply splices into the battery terminal on the alternator. But I have recently burnt up an alternator (it was still under warranty luckly) and I don't want to burn up my new one. So I think I may have had it wrong.

 

My research also tells me that Plug 1 goes to an idiot light. Since I check my guages frequently while driving I'm not worried about this unless I'm mistaken on its use.

 

Motor (and thusly the alternator type) is that commonly found in an 86 GMC Vandura.

 

THANKS for clearing up these myths for me. I should double post this on the electrical section also, but last time I did that I got called a "bad kitty". Being called that by a fellow mechanic is rather disturbing.

 

On another note... Can we get a spell checker on this webpage. I still don't know if I'm spelling Alternator right =)

[GabeRoc]

well, my last message did keep you from double posting this time, so the end justifies the means.

 

as for this questions you most likely have a Delco ST10 or ST12 alernator.

 

http://www.oldengine.org/unfaq/10si.htm

 

wiring should be the same for the ST12

 

gabe

[Guest tony78_280z]

Ya, I've read and downloaded and printed that page before. It is currently tucked into my Haynes Manual for safe keeping I thought it was very helpful. It does say to wire it strait to the battery cable. Like I said, all my research tells me that. But everyone I talk to says it should be switched.

 

So plug 2 SHOULD NOT be wired into a switch? And it will not burn up my alternator? These people I talked to are simply WRONG and don't know what they are talking about? They are spreading false rumors? C'mon reassure me here. =)

[Guest 77vegasz]

I run a one wire to the BAT terminal only and it works fine. I did have a wire from the positive battery terminal to #2, but eliminated it after 6 months when cleaning up the engine compartment, I could tewll no difference in operation. #2 does not need a switch, it will not burn up your alternator or run down the battery, or you can just not hook it up.

 

Jon

[Owen]

I've been researching this too and found that the net said #1 needs to be switched and #2 is the sensing wire for the idiot light.

 

There was another post on the 3-wire alts and it seemed that remote sensing is the best thing. Either way, is #2 for idiot light AND sensing?

 

I need to know this tonight.

Thanks,

Owen

[GabeRoc]

i was at knox generator today, so i asked the head tech there this very question. he said that #2 should be connected to the hot side, with out a switch. (then he pointed out it would be easier to just use the one wire regulator) as he has rebuilt, tested and installed more alternators than i will ever see (he looked to be ~50) i take his word to be gospel in this matter.

 

-Gabe

[Owen]

After more research, I found that #1 is idiot lite (optional) and #2 is hot.

 

#2 can be connected to the bat terminal on the alt, to the battery, etc. But Mad Electrical suggests hooking it up to the positive power distribution block for proper remote sensing. This is what I am doing.

Owen

[ThomaZ]

I might depend on the alternator design. My CSB had a Boch alternator on it which came from an -80 Audi/VW. It has an internal regulator.

 

When connecting the #2 wire direct to the battery per the JTR manual page 9-5 the battery was drained over night. Checking with an amp meter I had 2.7 Amps going from the battery with everything shot off. It dropped to zero as soon as I pulled out the #2 wire from the alternator.

 

My car electrician says I must wire the #2 wire over the ignition lock and that I have not destroyed the alternator. The car is in winter storage now so I haven’t rewired it yet and can’t confirm if his right.

 

ThomaZ