Engine Question on 3G Alternator.

[Exile]

The yellow-wire loop like in the picture above is sometimes utilized if the OEM charge cable AND sense wire are removed from the vehicle. If the OEM charge cable was left connected at the solenoid, the yellow wire is still sensing alternator output (and the loop is not necessary).

Could you tell/show me what the OEM charge cable, and sense wire look like/located? Im not familiar with those names, as far as what they look like, and are located at...

 

[James.Little]

I haven't removed any cables from the old 2G alternator, so does that mean I am good to go? I have spliced, soldered, and shrink wrapped the yellow and green wires, I seriously do not want to removed all that unless necessary. Also jrichker, thanks for the informative post!

 

[HISSIN50]

Could you tell/show me what the OEM charge cable, and sense wire look like/located? Im not familiar with those names, as far as what they look like, and are located at...

I don't have a pic of them. The charge cable is blk/orange and the sense wire is yellow. On the reg, the sense wire is labeled A if you want to trace it from the far end.

 

[Shakerhood]

Yes, I was driving the other day in the rain. I had my wipers, heater, lights and stereo going. I wasn't paying attention to my battery meter, until my stereo kicked off and the needle was in the red. When I finally arrived home the battery had enough juice to start the car one more time, then I had to hook up the battery charger. I was so glad I had my 3G waiting at the house for the install.

Speaking of, I do have the 3g installed (see attached photo). I ran a 4 AWG wire from the positive post on the alternator to a 200A fuse then to the positive side of the starter solenoide. Then I attached the green wire from the original harness to the provided green wire that came with the alternator, which I also did with the yellow wire (See original photo). From the old second harness that seem to be the output wires (two thick black and orange wires and one white). I just disconnected the wires and left them hanging around just in case.

Now, everything seemed fine, but the needle keeps moving slightly up and down, very suddle, is that normal? Also when I turn on something electrical, like the heater blower, it drops for a half a second then bumps back up to its original spot, also the lights dim for a slight second when I do that as well. Does this seem normal to everyone? Should I connect the black and orange wires to the battery post on the alternator?

Thanks for the help guys!

P.S. I have a few more pics of the install if anyone is interested.

Any particular reason you chose a 200 Amp Fuse, that seems kinda like overkill?

 

[James.Little]

Yeah it is. The only reason why is because I saw a kit on American Muscle and they had a 200amp fuse with it. I step it down to 150, which is still too high, but that is all they had. I really should pop in a 90amp fuse.

 

[mikestang63]

Yeah it is. The only reason why is because I saw a kit on American Muscle and they had a 200amp fuse with it. I step it down to 150, which is still too high, but that is all they had. I really should pop in a 90amp fuse.

If you are running a 130 amp alternator why would you run a 90 amp fuse. Try a 135 but the 150 should be fine.

 

[Shakerhood]

I have a 125 Amp fuse in mine.

 

[jrichker]

Any car that has a 3G or high output current alternator needs a 4 gauge ground wire running from the block to the chassis ground where the battery pigtail ground connects. The 3G has a 130 amp capacity, so you wire the power side with 4 gauge wire. It stands to reason that the ground side handles just as much current, so it needs to be 4 gauge too.

The picture shows the common ground point for the battery , computer, & extra 3G alternator ground wire as described above in paragraph 2. A screwdriver points to the bolt that is the common ground point.

The battery common ground is a 10 gauge pigtail with the computer ground attached to it.
Picture courtesy timewarped1972

Correct negative battery ground cable.

 

[James.Little]

If you are running a 130 amp alternator why would you run a 90 amp fuse. Try a 135 but the 150 should be fine.

I think it is a 160 amp alternator. The reason why is because I am not running the alternator at 100%, which would be 160amps, but I am running it about 60% which is about 95amps, I think. This holds true for all fox mustangs with a 3g alternator, unless you change to a smaller pully to create more RPMs.

 

[mikestang63]

I think it is a 160 amp alternator. The reason why is because I am not running the alternator at 100%, which would be 160amps, but I am running it about 60% which is about 95amps, I think. This holds true for all fox mustangs with a 3g alternator, unless you change to a smaller pully to create more RPMs.

The amp/alternator output is going to depend on

1. what size crank and alternator pulley you have
2. what rpm range you spin the alternator

General rule is the alt should spin about 2-2.5 x the crank speed. Still what is the point of popping a 90 amp fuse when you have an alternator that is capable of 160 amps. By having a 135 or 150 amp fuse you are still below the alternator output but have the amps to run things like a stereo, efan, on top of your A/C, lights, etc.

 

[James.Little]

When I say 60%, I am talking about absolute maximum RPM. The amp rating on 4 gauge wire is about 90amps. It is a extra precaution.