3G Alt guys, come in... need help

GreatWhite · Aug 5, 2006

So I just got done wiring in my 200amp fuse into my alternator install and I started the car to test it out with the stereo hittin hard... had the a/c, high beams, flashers and inside lights on... and i noticed it still dimmed some. I thought I followed the directions perfectly to what other people have done in their installs... Also, the alternator felt hot after running for just a minute or two... I'm assuming that's not normal...?

The original D-plug is connected as well as the white/black wire from the original power connector of the 2g into the stator wire connector... Then on the post I crimped connectors on the original orange/black 10awg wires as well as added the 4awg wire to the solenoid with a 200amp fuse inline... what could my problem be?

GreatWhite · Aug 5, 2006

trbkrb · Aug 5, 2006

Well, I for one would not reattach the stock wires to the alternator if you have the 4ga wire and fuse. If the fuse blows, then all the current will go through the stock 10 ga wires and you will not know there is a problem until you see smoke and fire under the hood.

I wired mine up, and while I don't see a lot of dimming, it does dim some when the lights and AC are on full blast. But no where near as bad as before with the 65 amp.

Is it a new or remanufactured alternator? If it is used, does it check out, output wise? Sounds like you have everything else in order. Maybe someone else has some ideas?

GreatWhite · Aug 5, 2006

I just figured having extra power wires wouldn't hurt in carrying the extra output... and I really doubt a 200amp fuse is going to blow with a 130amp alternator... and I bought it used off eBay from a car that was wrecked so I'm assuming it still worked up until it was crashed... I'm just not understanding why it felt hot...

GreatWhite · Aug 5, 2006

and do they only dim at idle... I just let it run at idle

glowstang93 · Aug 5, 2006

I agree with trbkrb. Do not attach the orange/black wires from the old plug to the new 3G. I didn't cut the plug off so I just taped it up, but since you have, just make sure you have it taped up real good so it doesn't short out under the hood if it touches metal grounding it out. The problem is that the output of the 3G is so much more than the stock 2G that the stock black/orange wires with the fuse links won't be able to handle the power.

I have the 95 amp 3G and I do notice some dimming or voltage drop however you want to say it, but it is nothing in comparison to the stock 75 amp 2G alt.

This may help too; idle output is not going to be as much as when your driving and the rpm's are up there.

Other than getting those stock black/orange wires disconnected from the 3G, it appears all else is good.

GreatWhite · Aug 5, 2006

So does anyone know why it's hot?

GreatWhite · Aug 5, 2006

and the 10awg's aren't taking it all themselves... the 4awg wire is on it too...

GreatWhite · Aug 5, 2006

and this site says to keep the 10awg wires should be left connected as the "4awg wire is there to supplement the routing of the extra power"

http://www.mustangmonthly.com/howto/26599/

jrichker · Aug 5, 2006

Under no circumstances connect the two 10 gauge black/white wires
to the 3G alternator. If the fuse blows in the 4 gauge wire, the two 10
gauge wires will be overloaded to the point of catching fire and
burning up the wiring harness.

The secondary power ground is between the back of the intake
manifold and the driver's side firewall. It is often missing or loose. It
supplies ground for the alternator, A/C compressor clutch and other
electrical accessories such as the gauges. Any car that has a 3G
alternator needs a 4 gauge ground wire running from the block to the
chassis ground where the battery pigtail ground connects.

The chassis ground and battery pigtail ground go to the bolt being
pointed at in the following photo.

Picture courtesy timewarped1972

GreatWhite · Aug 5, 2006

I have the ground. But do you think a 200amp fuse is going to blow from a 130amp alternator?

jrichker · Aug 5, 2006

GreatWhite said:
I have the ground. But do you think a 200amp fuse is going to blow from a 130amp alternator?

Not unless you develop a dead short to ground inside the alternator or to the 4 gauge feed wire.

8950HO · Aug 5, 2006

GreatWhite said:
and this site says to keep the 10awg wires should be left connected as the "4awg wire is there to supplement the routing of the extra power"

http://www.mustangmonthly.com/howto/26599/

Unfortunately there is bad info out there that you have to weed through.

I`ve seen a few 3g install articles that suck on the internet.

glowstang93 · Aug 5, 2006

jrichker said:
The secondary power ground is between the back of the intake
manifold and the driver's side firewall. It is often missing or loose. It
supplies ground for the alternator, A/C compressor clutch and other
electrical accessories such as the gauges. Any car that has a 3G
alternator needs a 4 gauge ground wire running from the block to the
chassis ground where the battery pigtail ground connects.

The chassis ground and battery pigtail ground go to the bolt being
pointed at in the following photo.

Picture courtesy timewarped1972

I found a metal grounding strap on my 2.3 running from the rear below the intake to the firewall. Is this the one that needs to be beefed up to 4awg? Just a little confused since the picture shows a ground on the fender.

Here is the strap on the firewall and I can see where it connects.

Here is the one on the fender. If I hook one end of the 4 awg wire to this bolt, where does the other end connect to? Does it connect to the back of the alternator case? I did notice a threaded hole there. If so, got any clue what size bolt (threads)?

Thank you in advance jrichker

jrichker · Aug 5, 2006

The strap is good, it just seems to disappear from most stangs after 15 years of various guys changing things around to suit their tastes. The 4 gauge ground to the common ground point is insurance that you have a good ground for the extra current that the 3G puts out. You can never have too good a ground or too much money...

glowstang93 · Aug 5, 2006

Was I right about the ground from the fender going to the alternator case?

What would you suggest, add a 4 awg to the firewall or do the one from the alternator case to the fender ground.

I trust your opinion.

jrichker · Aug 5, 2006

You can use any spot on the engine that has bare metal except the timing cover. The timing cover bolts tend to corrode, and that makes problems. The best spot is the battery block ground for the starter. The other end is best connected to the common ground point being pointed out in the previous post.

8950HO · Aug 5, 2006

I ran a 4ga ground wire from the block to one of the sway bar mounting bolts on the drivers side.

dec322 · Aug 5, 2006

glowstang93 said:
Was I right about the ground from the fender going to the alternator case?

What would you suggest, add a 4 awg to the firewall or do the one from the alternator case to the fender ground.

I trust your opinion.

Here is a thread that has a few pics of where srothfuss put his ground wire. I did it the same way and it works great. It is on page three....which is where the link will take you.

glowstang93 · Aug 5, 2006

Cool. I think I will connect one end to where the negative battery cable connects to the block and the other end back to where the ground is on the fender (where the small negative battery cable goes to). This will be very cheap, probably about $5-10 for a pre-made cable. Looks like a nice project for tomorrow afternoon.

Thanks

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