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Discussion Starter · #1 · (Edited)
I have upgraded to a G3 130 amp alternator and installed it correctly. I have already had the alternator and regulator checked out and are fine. The alternator doesn't charge the system, my engine runs off the battery til it's dead. My problem is that the green/red wire that runs off the back of the alternator and through the headlight harness isn't getting enough volts through it to turn on the alternator????? I'm seeing 3.39 volts through it. I thought perhaps I had a bad ignition switch on the steering column and replaced that. Any helpful ideas on a fix would be greatly appreciated.
 

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If you had the alternator checked out and it outs out proper voltage, you did not hook it up correctly. Are you running a 4 gugae wire over to the battery/solenoid?
 

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Discussion Starter · #3 ·
I am running the 4 gauge wire from the alternator to the battery side of the starter relay. I wired the stator wire correctly as well as the green/red wire.
 

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I am having the same problem on my '86 GT but mine is the stock alternator, the green wore with red stripe is not any getting power with the key on. What could cause this?
 

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Silverfox,The LG/R wire your talking about definitly should be 12v with the key on.
This wire comes from the ignition switch, thru the charge indicator light then to the Alt.
There are 4 connectors and one splice in all, including the ignition switch and alternator. The wire in question is LG/R all the back to the ignition switch.
There is probably a bad spot, (green-corroded), somewhere in there, if the ignition switch itself is OK. Your either going to have to trace it all the way back, or run a new wire to the ignition switch.
There is a small connector on the left side wheel well, below the starter relay you can check. Look for the LG/R wire and see if you get 12v there. At least you can eliminate half the circuit from there. All the other connectors and splice are not easily accesed.
If the problem seems to be from the 1/2 inside the car, I would look at the ignition switch itself, on the steering column. You can back-probe the connector for power, (or lack of power). At least the wire color is the same all the back , lol.
Hope this helps, G
 

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I just had a very similar problem on a swap I did.

Over at the starter solenoid, about 8 inches back or so, is where the old black/orange striped wires merge with another other wire (yellow/white stripe) from the alternator. That other wire is the voltage sensing circuit. They come together in a large black connector, and from there it they continue as one smaller wire (a grey fuse link). Check the continuity around that area. On the car I did, right after the large merge the fuse link was corroded internally. I replaced it and boom, went from 0 charge to 14.6v at idle.
 

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Id like to apologize to Silverforx for doubting him. i jumped to conclusions and 4 times outta 5, its soemthing that was hooked up incorrectly.
 

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Discussion Starter · #8 ·
Timmy, no sweat man. Sometimes the obvious things are overlooked.
Backseetluva, I do believe I have a bad spot somewhere in the wire and tried tracing it. I was able to get as far as the two pin gray plug, unhooked it, internally the plug looks fine. Even though my stang is a 87, I did get a chance to look at a friend's 1991 electrical schematics book. If I recall right that green/red wire switches to red/green and goes to the plug on the back of the instrument cluster behind the speedo side. Today I will test the voltage at the gray plug I mentioned but will probably end up fusing into the radio circuit to run a new signal wire.
Buffhomer, I still don't quite understand the whole fuesable link think. I did speak to a guy on the phone from a local alternator/electrical shop and asked him if fuesable links if bad, would cause my problem with the alternator turning on, he said no. So that brings me back to the wire trace.
I'll post again later today. I really would like to get past this, FFW tour is coming soon!!!
 

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SilverFox said:
...I still don't quite understand the whole fuesable link think...
A Fuse Link is a special type of wire with a special type of insulation and acts just like a fuse. Too much current or a short and the Link (wire) will burn out. The insulation will not melt or burn out, so it's hard to tell, but sometimes it's discolored.

The purpose of a Fuse Link is to protect the wiring and prevent a possible fire.
 

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First, the wire stays green/red striped all the way to the instrument cluster.

Secong, the fuse link WILL cause the problem you are having, I just went through that the day before yesterday.

Follow the black/orange striped wires from the alternator over to the solenoid. They will merge with the other yellow wire from the alternator in a large black connector/plug thingy. They will continue on to the solenoid as a fuse link. It's a smaller wire designed to work as a fuse, just Blown88GT said. Check the continuity around that area and see if the fuse link is messed up. The one I just finished up was, i replaced it and had instant full voltage.
 

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Is this the same wiring setup for a '86 GT? I am having the same problem except I have no voltage on the green/red wire on the alternator regulator. Do the '86 have the same dash circuit between the ignition switch and the alternator regulator. Please help I have no ride because my car is not charging.

Thanks,

Clint
 

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buffhomer said:
Secong, the fuse link WILL cause the problem you are having, I just went through that the day before yesterday.
I dont think the fuseable link has anything to do with the problem Silverfox is having. I dont mean to flame or anything, but if you read the original post, you'll see that he is not getting voltage on the LG/R wire.
This circuit is independant until it gets to the alternator connector, and it gets voltage from the iginition switch.
The fuseable link protects the rest of the electrical system, and yes- if it burnt, the Alt wont charge- or more accurately- the charge wont get past the burnt link.
If that fuseable link was burnt, he would still get 12V at the LG/R wire.
I hope this clears thing up a bit.
 

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Discussion Starter · #14 ·
UPDATE......
I was able to get power to the alternator through the green/red wire by bypassing the rest of the green/red wire. However the system is still not charging. I ran the test light between the battery and cable and I do have a short in the system. I think the short might be big enough to dampen any charging capability of the aIternator? It was getting late so I called it quits for the night. Tomorrow night when I get home from work, I will start individually testing everything attached to the starter relay, including fuseable links. I appreciate the input guys and will let you know what I find.
 
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