3G swap... now battery light turns on

No.11 · Feb 27, 2012

had no problems yesterday, but on my way into work I stopped to pump gas. when I turned the car back on the battery light flashed. then it went on solid until it idled for a few seconds. after driving it would turn on and sometimes off, and when it was on while I was idling I could hear the fuel pump whining weakly.

yesterday it checked out fine. 12.7 volts while off, 14.7 at idle. I did notice that as it got warmer, voltage kept dropping, eventually to 14.3. based on this info, what could be wrong? I want to try and be prepared in case I get stuck here without my tools and multimeter and stuff to check properly.

No.11 · Feb 27, 2012

wiring was as instructed. the two orange black wires crimped and soldered to the terminals provided, these as well as PA power wire went to the gold terminal, then the black white wire soldered onto the supplied white wire. power wire kit with fuse mounted on battery tray and hooked up to the + on the starter solenoid. belt is still on tight. wish I had my multimeter and it wasn't Monday (I rush off to school and then rush back to 2nd job.)

RUNINAGT · Feb 27, 2012

I just did mine last week. I taped off the old plug with the blk and orange wires. I ran a different 4g wire from the back of the alternator over to the solenoid. Then placed a 12g fusible link from the solenoid to the battery. I only used the white wire off the original plug.
I purchased a NEW alternator for the year 94-95 5.0 Mustang. So far so good. My only issue was the belt squealed bad, so I replaced it with a new one and squealing went away.
My 1st thought is the possibility of a faulty alternator??

Mustang5L5 · Feb 27, 2012

Make sure the white wire (stator wire) is hooked up and tightly connected.

No.11 · Feb 27, 2012

oh yeah forgot to add the original stock cable of course went back onto the new alternator.

I'm thinking yeah maybe a faulty alternator. I purchased it off a guy on Craigslist. he has quite a few ads on there. I hope he didn't screw me over. he originally had the alternator listed as brand new pa performance. when I got home I saw it was a Chinese made WPS (world power ssts alternator). not a pa performance builder right? alternator looked completely clean so I couldn't see it being a used one. bolt hole areas didn't look grooved or anything. so I figured it was still an ok deal... but if it wasn't a good alternator wouldn't it not have given me 14 volts?

No.11 · Feb 27, 2012

will check on that mike, thanks. pretty sure it was on tight, even heat shrunk it. but will check my soldering also for good measure.

RUNINAGT · Feb 27, 2012

You used the original stock power wire? Sure it will work, but from what I have read that's a lot of current going through that small wire? That is why most upgrade to a larger 4g. Just don't want ya to find out the hard way that the wire is not thick enough.

No.11 · Feb 27, 2012

wait are we talking about the same wire? I had the power wire kit from pa performance. the other wires should come out?

RUNINAGT · Feb 27, 2012

oh you had a kit, ok, I took it as you were using the power wire that was original on your car.? I bypassed mine and routed another power 4g wire.

jrichker · Feb 27, 2012

No.11 said:
wiring was as instructed. the two orange black wires crimped and soldered to the terminals provided, these as well as PA power wire went to the gold terminal, then the black white wire soldered onto the supplied white wire. power wire kit with fuse mounted on battery tray and hooked up to the + on the starter solenoid. belt is still on tight. wish I had my multimeter and it wasn't Monday (I rush off to school and then rush back to 2nd job.)

The instructions you have ae not correct. Under no circumstance, connect the black/orange wires to the 3G alternator.

Here is the reasoning behind using only a single 4 gauge fused power feed to the alternator. If you use the two 10 gauge black/orange wires in addition to the 4 gauge wire, you have two fused power feed paths. The total current capacity of the wiring is the sum of the fused paths. The 4 gauge path is fused for 125 amps, and the two 10 gages wires are fused for 60 amps. That is a total of 185 amps, which exceeds the capacity of the alternator. Overload can occur without the fuses blowing, damaging the alternator.

The worst case scenario is that the alternator develops an internal short to ground resulting in a catastrophic failure. The initial short circuit surge current is limited by the resistance of the wiring. The current in a parallel circuit divides up according to the resistance of the branches. If the 4 gauge fuse opens up first, the two 10 gauge black/orange wires will be carrying the short circuit surge current. Depending on the time lag of the fuse links, they may open up before a fire starts or they may not.

Stangnet 3G install sticky http://www.stangnet.com/mustang-forums/646825-3g-alternator-install-how.html#post6673702

Alternator wiring

Starter solenoid wiring 86-91 model cars
Connect the fused 4 gauge wire to the alternator and the battery side of the starter solenoid.

Starter solenoid wiring 92-93 Model cars.

Take the alternator to your local Auto Parts chain store (AutoZone, O'Riley's, Advanced Auto Parts, etc) and they will test it for free.

No.11 · Feb 27, 2012

so... this write up by a customer on americanmuscle's website is the wrong way to do it?

http://1.cdn.lib.americanmuscle.com/files/95304_95311.pdf

and all I need to to is disconnect the two orange/black wires from the gold terminal? and tape them up and leave alone? and I need nothing else to get this working?

No.11 · Feb 27, 2012

ok did that, seems like its charging, not quite at the 14.5 volts I was getting yesterday on the battery. it's at around 13.3 right now. that ok?

No.11 · Feb 27, 2012

if not I guess ill have to take it to get checked.

edit: according to the installation manual from pa (not the American muscle customer one), I should be fine if I'm charging at over 12.5 volts at idle. guess I'm good to go. a little test showed good results. I turned the high beams on, then put the windows all the way down, and kept holding the buttons down. normally, I would see the headlights dim and the revs drop quite a bit. yesterday they did this considerably less. but today! today the revs seemed not to drop at all! thanks all for your help!

RUNINAGT · Feb 28, 2012

My old plug with the orange and black wires for now is simply just tapped off. I need to cut it and cap off the ends I guess.

So you did end up running a 4g wire to the solenoid?

No.11 · Feb 28, 2012

yep I was running the 4g to the solenoid the whole time... and then the orange black wire also. took those off so now only the 4g to solenoid.

should I get a 4g ground as well?

RUNINAGT · Feb 28, 2012

I did not attach any grounds. Figured it grounded through the brackets and mounting bolts?
Good question though, do I need a different ground?

jrichker · Feb 28, 2012

No.11 said:
so... this write up by a customer on americanmuscle's website is the wrong way to do it?

http://1.cdn.lib.americanmuscle.com/files/95304_95311.pdf

and all I need to to is disconnect the two orange/black wires from the gold terminal? and tape them up and leave alone? and I need nothing else to get this working?

Totally wrong...
There are a lot of Bozo's who try to do electrical stuff. They can't spell Ohm's law much less tell what it means. NEMA electrical code wire size chart - see See http://lugsdirect.com/WireCurrentAmpacitiesNEC-Table-301-16.htm

The two 10 gauge wires are barely adequate for the 65 amps, much less 130 amps.

Follow the instructions in my previous post. I will put my electrical expertise up against theirs any time. Follow their instructions and you are asking for trouble.

See the wire size to current capacity chart below.

jrichker · Feb 28, 2012

double post...

RUNINAGT · Feb 28, 2012

so I guess mine is correct?? How about the ground?

Blown88GT · Feb 28, 2012

No.11 said:
so... this write up by a customer on americanmuscle's website is the wrong way to do it?

http://1.cdn.lib.americanmuscle.com/files/95304_95311.pdf

and all I need to to is disconnect the two orange/black wires from the gold terminal? and tape them up and leave alone? and I need nothing else to get this working?

He copied the writeup from someone else & they got it wrong, too. He could have copied from someone who got it right. You don't even have to cut the connector off, don't have to tape it up & worry about it shorting out. Mine's still part of the harness, buried beneath the rest of the harness. As for "I will put my electrical expertise up against theirs any time", I no longer waste my time on such nonsense. I have forgotten more than they will ever know in an entire lifetime. Years ago, I did a writeup for MM&FF which got published. I'm sure they didn't understand it, either.

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