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Topic: alternator

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alternator (1/15)
6/22/14 1:58pm

Bags74Vette
Former Member
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Joined: 6/22/2014
Posts: 46

I noticed that the brown wire on the left plug of my alternator came loose. Car seems to run fine. Not sure how long its been that way. Do I need to attach it back? Thanks for any help

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Re: alternator (2/15)
6/22/14 6:20pm

dyoes
Former Member
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Zachary, LA - USA

Vette(s):
1974 L-48 Auto. Just your basic Vette. GM crate motor w/vortec heads and intake. Crane cam. Scorpion rockers, Edelbrock carb. Lots of parts still in boxes... :(

Joined: 1/27/2013
Posts: 201

It's likely a ground wire and probably won't affect a thing. But it's never a good thing to leave loose wires hanging around... I'd do a continuity check and make damn sure it's what you think it is, and hook it back up.

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"Let them that don't want none have memories of not gettin' any."
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Re: alternator (3/15)
6/23/14 12:54am

daveo76
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Vancouver, WA - USA

Vette(s):
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

Joined: 8/25/2005
Posts: 857

I'm pretty sure that's the one that broke on mine and I didn't notice either until one day while running errands (multiple engine stops and starts) it started cranking slower and slower and eventually the battery wouldn't turn the engine over - had to get my wife to come give me a jump. Pretty sure that broken wire prevented the battery from being charged. Better fix it.

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1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

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Re: alternator (4/15)
6/23/14 12:09pm

rraider1
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Woodland, WA - USA

Vette(s):
1977 T-Top,350,Auto Black Ruby Pearl,Steeroids R&P conversion

Joined: 10/14/2003
Posts: 1165

The brown wire is for the GEN warning Light and should be fixed. Your local parts store should have a replacement plug with wires installed. you would splice the new plug in (make good connections)

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Re: alternator (5/15)
6/23/14 12:15pm

Adams' Apple

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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 20129

According to the wiring diagram, the brown wire comes from a fuse link down by the starter. No "Gen" warning light on this model....just the amp gauge. It does need to be repaired,at any rate... Thumbs Up

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Joel Adams
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Re: alternator (6/15)
6/23/14 7:36pm

Bags74Vette
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Joined: 6/22/2014
Posts: 46

thanks so much

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Re: alternator (7/15)
6/23/14 7:39pm

Bags74Vette
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Joined: 6/22/2014
Posts: 46

Thanks for the info

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Re: alternator (8/15)
6/23/14 7:57pm

Joel,

You've got me curious now. Here's the setup in my car with the offending wire. However, I don't see the brown wire on the diagram. The two reds join together in the wiring diagram, and the heavy black is obviously the ground that's shown. The brown doesn't appear in my drawing. Where does the darn thing go? I'm OCD, so I'll probably go trace it out until I figure it out...

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"Let them that don't want none have memories of not gettin' any."
- Brother Dave Gardner

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Re: alternator (9/15)
6/23/14 8:15pm

rraider1
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Woodland, WA - USA

Vette(s):
1977 T-Top,350,Auto Black Ruby Pearl,Steeroids R&P conversion

Joined: 10/14/2003
Posts: 1165

sorry I first look at my 77. Follow the wire from terminal 1 it runs to a splice point to ground. Joel would this effect operation not 100 % sure of why the ground if not hooked up to a light bulb.

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Re: alternator (10/15)
6/23/14 8:54pm

I figured it out for my car, anyway.

My entire harness is from a '75 so I could eliminate the cable drive tach. I had looked at the '74 diagram on my previous post.

(On an unrelated note, the tach just died. Lots of good THAT swap did me!)

The '75 diagram shows the wire. Tracing it out, it joins to the heavy Orange wire on the ignition switch on the column... From there, the orange wire goes to the heater motor resistor. And since I have Vintage Air and not a factory fan blower, I'd guess that the brown wire is doing diddly squat (at least in my car).

And with that, gentlemen, I've officially given myself a headache.

Dead

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"Let them that don't want none have memories of not gettin' any."
- Brother Dave Gardner

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Re: alternator (11/15)
6/23/14 10:31pm

Adams' Apple

'74 alt diagram. Brown from the solenoid. The red section is a fuse link. I added the colors to make it easier to see.

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Re: alternator (12/15)
6/24/14 12:26am

Bags74Vette
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Joined: 6/22/2014
Posts: 46

I haven't had a problem yet with my wire. Plenty of battery juice. Maybe its for nothing at all

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Re: alternator (13/15)
6/24/14 2:25pm

rraider1
Former Member
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Woodland, WA - USA

Vette(s):
1977 T-Top,350,Auto Black Ruby Pearl,Steeroids R&P conversion

Joined: 10/14/2003
Posts: 1165

Joel I am missing something (easily confused) looking at your diagram B would be the heavy gauge wire Alt output, 2 is spliced to that wire for regulating out put voltage. 1 which on later models goes to the Gen light but on this year they have it going to ground. what am I missing?

And a dual terminal connector. (Repair pig-tails for this connector available at any auto parts store. Or, salvage with alternator if pulling the alternator from a vehicle).
The #1 Terminal. (Marked with a �1� on the case)
This terminal is used to connect to the dash warning light.
For the warning light, a lamp is wired in series with a switched voltage source. During normal operation the lamp stays off. If the regulator is damaged, the #1 terminal provides ground, and the warning lamp will light. Usually.
This terminal is also active on 1 wire regulator equipped 10SI alternators.
The #2 Terminal. (Marked with a �2� on the case)
This terminal is used to excite the 10SI into operation. (3-wire 10SI)
It is connected to the battery positive.
For simplicity you can connect the #2 connector pigtail directly to the �batt� terminal on the alternator.

|UPDATED|6/24/2014 11:25:02 AM (AZT)|/UPDATED|

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Re: alternator (14/15)
6/25/14 12:51pm

Adams' Apple

Bob, I think these are wired like that because they have AMP gauges, where the later cars have voltmeters.The diagram does looked kinda silly, with the batt feed AND the brown from the solenoid spliced together, along with other hots....makes ya wonder why. It has to do with the wiring for the amp gauge. Big smile

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Re: alternator (15/15)
7/2/14 1:01am

Bags74Vette
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Joined: 6/22/2014
Posts: 46

Found out that brown wire was my problem. Got it fixed with a new plug

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