1jz alternator wiring

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kas14slider

New Member
May 18, 2010
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State College, PA
Hi guys, I have a 1jz in my s14 and the other day my battery stopped charging. I went through one new battery and now I am on my second new battery. I took the alternator out and took it to get tested and it was good. So I assume there is a problem with the wiring. Now I didn't do the wiring myself on this car so I decided to take a look. I have the round 3 wire connector on mine. Alternator is an sc300 one. Based on what I found online the 3 plug connecter should have:

IG (black/yellow) 12v with key on engine off.
L (green/yellow) I think this needs 12v with ignition on
someone said that the L wire needs to be connected for the alternator to energize.
S (white) 12 v constant

But what about the big wire you bolt to the side of the alternator? Mine is a white wire with a rubber cover on the end and it gets 12v constant.

So I tested mine and I got:

IG (black/yellow) Key off: 0v Key on: 0v
L (green/yellow) Key off: 0v Key on: 0v
S (white) Key off: 0v Key on: 12v

Big white wire : Key off: 12v Key on: 12v

So I don't know if this is how mine always was and the car ran fine or something happened to the wiring. Maybe my big white wire was always my 12v constant and the white wire on the alt plug was my ignition. But this doesn't seem right to me that only 1 of the 3 wires gets power when the key is on. Should I just try to rewire that 3 wire plug so it gets the correct volts?
 
K

kas14slider

New Member
May 18, 2010
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State College, PA
Just checked all my wires for continuity against chassis ground to see if they were grounding out. None of the wires were getting anything except the white wire on the plug read 1.5 ohms and also made a feint beep with the multimeter on the buzzer setting. So I does that mean that wire is getting barely touching a ground somewhere?
 
IBoughtASupra

IBoughtASupra

New Member
Mar 10, 2009
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Queens, NY
You will need to follow each wire and see where it is grounding out. Is the alternator charging at all when you tested it in the car?

Does the battery light come on when the alternator was on the car?
 
K

kas14slider

New Member
May 18, 2010
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State College, PA
Well I would drive the car and after a bit all my electronics would slowly die out and then the car starts sputtering and not running. But I don't remember if the battery light came on.
 
K

kas14slider

New Member
May 18, 2010
77
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0
State College, PA
A member on supraforums just responded to my problem:

I posted this last month...Don't do shit till you read each wire's purpose below. This should answer all your questions as this is simple wiring.

Black/Yellow:
Used For - Ignition 12v to power regulator and alternator windings
How Its Hooked Up - Ignition switched power aka any 12v switched source.
Size Fuse Needed - 15amp

White:
Used For - Sense charge
How Its Hooked Up- AM1 constant power aka any main power feed.
Size Fuse Needed - 40amp

Yellow with green stripe:
Used For - Battery warning lamp in gauge cluster that is also the regulator ground
How Its Hooked Up- grounded to cluster to any lamp that has 12v source on the other side.
Size Fuse Needed - 7.5amp
 
K

kas14slider

New Member
May 18, 2010
77
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0
State College, PA
Now I am a noob at wiring but can I find a wire that already runs through the necessary size fuse and splice it in? Like if I find a 12v switched wire running off a 15amp fuse in my fusebox under the hood, can I just splice a wire off of that to the alternator wire? Or should I run all new wires from somewhere and install 3 new fuses for each of them.
 
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