Painless Harness in 70 Mustang with 3G alternator?

callys

Member
Oct 14, 2005
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Hello again,

My Mach 1 was in a fire, and I previously posted that I was going to try to make a serpentine system work with my 351.

I got a complete junkyard 5.0 setup, and a four-eye water pump, and all I had to do was frabricate a small bracket to stretch from the water pump holes to the right accessory mounting setup with the 351's taller deck height. Ford sells a .950" crank pulley spacer, so I have the setup ready to go on with serpentine.

At the time, however, I am going to a taurus electric fan. So I really need a higher output alternator. I want to use a 3G since it should be an easy bolt-in with the 5.0 bracket.

Here is my problem:

painlessmd5.jpg
http://g.imageshack.us/img100/painlessmd5.jpg/1/

The Painless Wiring Harness (my original harness burned up) calls for the power to the internal fuse block to be run off the alternator...

Isn't the 3G alternator a 1-wire unit? Does it only have 1 post on the back? How would I make this setup work?

Also how would I setup the ignition switch? On the 70 it runs through the voltage regulator.

Is there someway to just use the 3G with a voltage regulator?

Thanks
 

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I found this guide

21965d1166149617-late-model-alternator-early-harness-3ginstall.jpg


I guess that information will be largely the same for modifying the Painless harness?

It looks like the major difference is on the Painless harness the B+ terminal goes to the interior of the car to the fuse block, then comes back out to go to the starter solenoid, whereas on the OEM harness the B+ goes to the starter solenoid terminal and the fuse block gets its power from somewhere else?
 

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The Painless Wiring Harness (my original harness burned up) calls for the power to the internal fuse block to be run off the alternator...

Isn't the 3G alternator a 1-wire unit?
Does it only have 1 post on the back?
How would I make this setup work?

Also how would I setup the ignition switch? On the 70 it runs through the voltage regulator.

Is there someway to just use the 3G with a voltage regulator?

#1 No, the 3G is not a 1-wire unit.

#2 It has only one B+ post on the back and it should go to the battery Pos terminal.

#3 The Painless harness looks like it mimicks the stock harness setup for an Amp Gauge. The old amp gauge loop is not compatable with high output alternators. If the output is tied to the painless harness on a 10 gauge or smaller wire, the 130A will fry it. The yellow/wht wire is the sense wire and should be tied to the B+ close to the battery.

#4 The LtGrn/Red wire goes to an ign source thru the alt lamp or about a 560 ohm resistor.

#5 The 3G is internally regulated and the old external Voltage Regulator is not needed.

Here is a link to a thread with more info:

http://forums.stangnet.com/762671-pa-performance-3g-install.html
 
Is there a place to buy just the OEM engine bay wiring harness? The Painless seems like kind of a pain (haha) with regards to having to replace the entire cabin and trunk harness to make it all work.
 
Is there a place to buy just the OEM engine bay wiring harness? The Painless seems like kind of a pain (haha) with regards to having to replace the entire cabin and trunk harness to make it all work.


yes you can buy them from just about any of the big mustang parts suppliers, mustangs unlimited usually has decent prices on them