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Discussion Starter #1
I am having problems with my s197 GT, and the p0340 code. I had the code for a while, and my alternator finally went out. I replaced it and everything went south. Here is what happened the first time:


Hooked up new alternator, charged battery, connected everything, and when connecting the harness back up to the battery, there was some discharge... I thought, it was just arcing from insufficient contact. I was wrong and when I pushed it down completely the harness glowed, and then set fire (JUST the alternator harness).

Now, where I am today:

Replaced harness, and connected everything back up. went to connect the battery, and I am hearing discharge again. It isn't arcing like it was, but I am paranoid as **** since I can't afford another repair bill anytime soon. Like I've always been told, negative first, then positive. SUPPOSEDLY, and I don't necessarily believe this the more I think about it, on my s197 I am supposed to hook up the positive before the negative? I found this on the Internet somewhere, and since the Internet is full of unreliable information, I am double checking everything I can.

Like I said, I am not down with messing up my car again, so if anyone can help me out that'd be awesome. I just want to know if the little bit of discharge I am hearing is anything to be concerned about, like I think it is.

I unhooked the battery until I can get accurate, reliable, solid info that I can continue on with.
 

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Thats a nasty sounding problem. Where did you get the alternator, sounds like a bad alternator thats shorting out to ground.
 

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Yeah it sounds like a short in the alternator. Take it back to wherever you got it for an exchange before proceeding further. I’m surprised the fusible link didn’t fry first, that’s supposed to protect the harness from that sort of thing.
 

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Discussion Starter #4
the fusible link, what does it look like? Sorry, I am quite illiterate when it comes to electronics. I am not a fan of working with or on them, and this most recent experience is not helping at all
 

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A fusible link is just a smaller gauge of wire that’s in series with some larger wire. It’s designed to be the weak point and to open like a fuse in event of a serious overload to protect the rest of the harness and system. It’s typically covered in silicone insulation for durability and heat resistance. I know where it’s at on my 4.0, but am unsure about the location on the 4.6. It should be in an open accessible location though, and mine’s covered with a different color of cable sheathing (blue in this case) than the standard black.
 

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Have the alt checked, make sure you didn't pinch
any wires near it.
The reason you hook up the positive side first is
so if wrench touches body metal you do have a short,
when doing negative it won't matter since that is ground.
 

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Discussion Starter #7
awesome, it was the blue section that went up in flames. Alt is out, and will be tested tomorrow. If it comes back as being fine, what next? Start looking for a short?

I'm skeptical it could be anything else, since I had no electronic issues before the new alt. But just in case, I am hoping to be able to drive my mustang tomorrow if possible.
 
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