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1G to 3G alternator conversion

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This is specifically for a 69 and 70 (because they are brother cars) but the concepts apply to all. Frankly the only reason I did the 70 is because it was the first year to have fuse links, and I wanted to see how they did it. I've been working with PA Performance on a 3G alternator and found their instructions woefully lacking. FYI a 1G is generation one, etc., and the 3G is prized for its high amp output at low rpm. The 69 is on page 1, the 70 on page 2 and all the notes (which you really need) are on page 3 of the attached PDFs.

3G alternator wiring pg1.pdf 3G alternator wiring pg2.pdf 3G alternator wiring pg3.pdf

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someone on another forum asked what was meant by note 2, so...


Its best to show what happens with pictures.
To explain this I need to shift into teaching mode- mind you I’m not a teacher, but I am an Electrical Engineer. First, what is a short circuit, or short? A short is when a circuit has less resistance than intended and is usually near or approaching zero ohms. Lets say that the wire leading to the fuse box gets frayed and connects (shorts) to the chassis.
We will estimate this short is 0.1 ohms, so using Ohms Law, I=E/R =12v/.1ohms = 120 amps. That's enough to melt the 12 ga. wire used to supply all the power to the car in the original harness.
The manufacturers instructions say to install the alternator this way:



Su1GISN.jpg



This is a guesstimate based on perceived wire lengths from the wire diagram. I won’t bore you with the calculations, but wires 38A and 38B will flow about 54 amps while 38 and the 4 ga. wire will flow about 66 amps.
The 150A fuse link will not open because the amps are too low, but all the 12 ga. wires 38, 38a, and 38B will become a fuse and melt. This occurs at about 38.3 amps in a high heat area like under the hood where wire resistance goes up.



9cVeraG.jpg


This is the preferred method of installation.
The wires are not connected at note 1 and a 14 ga. fuse link has been installed at note 2. Since the 14 ga. fuse link is smaller than the 12 ga. wires 38, 38A, and 38B, the fuse link will blow and the wire harness will be saved. I would rather be stranded by the side of the road than burn-up the car.


BSVbgyZ.jpg
 

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Perhaps the biggest problem with the PA Performance alternator (besides their faulty instructions) is that it is unique and needs their special regulator. If you break down on the road you can't go to the local auto parts store and get a new one, because your wiring won't match. Here is a look at a Ford type 3G that you can get from AutoZone or what have you. This is shown in a 68. I have checked 66,68,69, and 70, and they are all "electrically" the same in the charging system and power wires. That isn't to say that the colors don't change, or the wire numbers, or the wires may not be connected in exactly the same spot- but the electrons go to the same places.
This is a stock 68:

u6pFWZZ.jpg


Here it is with a Ford type 3G. The ammeter won't work and must be replaced by a voltmeter (on 654 Y if you like). The line that runs to "I" has an idiot light and a resistor. The light is optional. The resistor may be anything from 500-560 ohms 1/2w. Some guys leave it out and wire it direct to I with no light or resistor. This works BUT if you leave the key on with the engine off the alternator will still be on and it could cook your internal regulator. Heck, even with the resistor it may- there doesn't seem to be any consensus. The size of the mega fuse and the gauge wire is dependent on the size alternator you get. There is a problem with circuit this that I will discuss later.

JGF4sq7.jpg


This one shows what happens if you get a short on one of the main power lines- in this case to 25 BK/O has been frayed or pinched and is connected directly to chassis. Wires 38A, 37, and 25 are all 12ga wires that turn into fuses and melt.

Eb55sFF.jpg


This is the best approach, prevents melting your main harness, and is what Ford finally did in 1970. Its easy and since you are in there anyway, just add a 14ga fuse link or fuse, and that will melt instead of your harness.

5Tm1cow.jpg


This chart shows Ford 1G, 2G, and 3G alternator outputs. Since the 2G is only slightly better than the 60A 1G and it was plagued with recalls for fires, I wouldn't recommend it. More isn't always better and if you want to keep the stock look with V belts then go with the 95A. It will still need two V belts (you can extend the next belt forward to make it work) and you won't have to go with a serpentine system that requires electric radiator fans that suck up another 20 amps. Choose wisely.

UjgHM0V.jpg

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Nicely done.  Like the drawings.

The fusible link was used on later cars due to the upgrade to the alternators that had build in voltage regulators.  (aka diode trio).

The link is there to protect the connection from the battery to the alternator stator diodes, in case of a diode short to ground. It is not there to protect the rest of the electrical distribution system.  

The second alternator fuse (smaller fuse) is there to protect the field (rotor)

Passive (non-mechanistic) failures of wiring are really not postulated as an initiating event that required fused protection.  Fuses are used where shorts from active (switched, resistive, or rotating) components are plausible, and the fuses are designed to protect the wiring.

 

 

 

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Bringing an old (but great) post back to life...

the PA performance instructions say to connect their green/red wire (from alternator connector) to an ignition wire (also green red) from the engine.  The illustrations in the first post say to connect the green/red from the alternator to the orange wire from the voltage regulator.  This wasn't addressed in any of the Notes.  Is this a mistake on the PA Performance instructions?

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I think what you are describing is in my first post, picture "3G alternator wiring pg1" in the picture titled "69 Mustang with 3G". The field on the PA Performance regulator is connected to wire 35 orange, goes through a plug and connects to a green/red wire that goes into the PA Performance alternator.

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Yes, thanks for being more accurate.  That is the picture and wire that I am referring to.  

In the instructions that came with the PA Performance alternator, it says to wire the green/red wire (from their alternator connector) to a 12V ignition source.  This is different than your described wiring.  I've wired mine according to your illustration, however this difference confused me a bit.   I don't know why PA's instructions say to use the 12V ignition source (for it's green/red connector wire) rather than the Field output of the regulator, so thought I'd mention it here.

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On 1/28/2020 at 11:10 AM, Flanders said:

Yes, thanks for being more accurate.  That is the picture and wire that I am referring to.  

In the instructions that came with the PA Performance alternator, it says to wire the green/red wire (from their alternator connector) to a 12V ignition source.  This is different than your described wiring.  I've wired mine according to your illustration, however this difference confused me a bit.   I don't know why PA's instructions say to use the 12V ignition source (for it's green/red connector wire) rather than the Field output of the regulator, so thought I'd mention it here.

Just wanted to verify if this is working yet per my diagram?

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Hi Mach 1 Driver,

Thanks for the wiring diagram. I have just changed my alternator to single wire 100A unit and 100A cable to solenoid post ( I need to add fuse). The wiring diagram I have didn't match the colour code of my 69 amp meter car.

I have 69 sports roof fitted with a Aussie late 70 ties Falcon 351C by PO. Alternator was 60A with external electronic regulator not shore if it was from 69 or came with 351C.

How long is  38A shunt wire and where in car / loom is the link to 38BK, 37BK/Y, 654Y ?

Cheers Paul

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7 hours ago, pgold said:

How long is  38A shunt wire and where in car / loom is the link to 38BK, 37BK/Y, 654Y ?

Cheers Paul

Midlife is our harness expert- he is in the harness refurbishment business and knows more than anyone else on the planet about Mustang harnesses. Perhaps he will chime in here.

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Indeed I will!  And: I have no idea.  The shunt circuitry is designed based upon very small differences of wire resistance due to wire gauge, length, and joint location, and is something that I cannot (will not? care not to?) fool around with.  The circuit is designed to allow milli-amps to the ammeter while the rest of the circuit runs on the order of 30-60 amps.  You need a micro-ohm meter to do it correctly and I do not know Ford's design in enough detail.  After 50+ years, wire resistance changes due to age/corrosion making it impossible to reverse-engineer the circuitry with enough fidelity.

 

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  • Midlife
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Indeed I will!  And: I have no idea.  The shunt circuitry is designed based upon very small differences of wire resistance due to wire gauge, length, and joint location, and is something that I cannot (will not? care not to?) fool around with.  The circuit is designed to allow milli-amps to the ammeter while the rest of the circuit runs on the order of 30-60 amps.  You need a micro-ohm meter to do it correctly and I do not know Ford's design in enough detail.  After 50+ years, wire resistance changes due to age/corrosion making it impossible to reverse-engineer the circuitry with enough fidelity.

Hi Midlife,

I'm a retired electrician so I understand the theory. 

I'm not planing repairing amp meter.

I still have some of the external regulator wiring and 38BK 38A BK to remove to tidy up wiring. I just did what was required to get car back on road to do a weekend run.

Stanthorpe is a area 2.5 hours drive SW from Brisbane doing it tuff from drought and bush fires. They have had some rain and country looks green but their dam is empty and trucking water in for town water. No grape harvest this year - no work for backpackers -  so they are not in town spending money in local business.

So 13 mustangs and passengers spent the weekend in town doing wine tours , function at local hotel and dining at cafes and motel accommodation. We also raised a nice donation for local Volunteer Fire Brigade.

Sorry for getting of topic.

Cheers Paul.

 

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On 1/31/2020 at 5:08 AM, Mach1 Driver said:

Just wanted to verify if this is working yet per my diagram?

Reviving this, now that I've been able to start my car!

My PA Performance alternator doesn't seem to be charging the battery.  I've connected it as per your pg1 instructions, however I'm wondering about the F from the PA Performance regulator that goes to the orange wire, then goes to the red/green wire on the Alternator.

If the PA Performance alternator is internally regulated (which I believe they are, according to their website), then what is the "F" output of the regulator doing in your diagram (pg1)?  It's ultimately going to the green/red of the alternator but I'm not sure what the voltage is on it.  The PA Performance instructions say to wire the green/red wire on their alternator to a 12V ignition voltage (ie. like the green/red wire that goes to the S pin of the original alternator) so I believe that's why my alternator currently isn't charging the battery.  

Thoughts?  If their regulator is a dummy one, then the F output isn't doing much (I've pinged them to get more information, but figured you've already been talking to them)

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I've got more digging to do.  Got this from PA Performance (nice quick support!).

My car never had the 3-pin connector to the alternator, so something else may be at play here.  I need to see what voltage I've got out of the F pin of their voltage regulator, but I believe the instructions below match your pg1 diagram (step 12 is the orange wire).

 

462802C Kit - Express Instructions

This instruction sheet is a supplement to the main installation instructions provided in the kit, and not meant to replace or contradict the more detailed steps.  Some more experienced installers prefer a simple guide.

  1. Disconnect Negative battery cable on car battery and move to the side.
  2. Mark wires on existing alternator as ST, FLD, B+ and Ground (if there is a ground)
  3. Disconnect fender mounted external regulator plug
  4. Remove fender mounted external regulator box
  5. Install new PA Performance fender mounted external regulator box
  6. Reconnect plug
  7. Replace alternator per alternator instructions
  8. Connect the 3-Pin alternator plug provided in the kit to alternator
  9. Connect Yellow wire to B+ Post
  10. Connect White/Black wire to Stator tap on alternator.
  11. Tape the original ST wire as it is not used but may have power
  12. Connect FLD wire to new Green/Red wire in kit
  13. Connect B+ wire to alternator
  14. Connect Ground (if there is one)
  15. Connect Negative battery terminal to battery.

You will have power at the green/red wire with the ignition key in the run position, no power on this wire with the ignition key off

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The 69 comes with a plug to the alternator, so if you don't have one then a previous owner has made some changes.

The PA instructions are unclear to the point of making no sense. Lets go down their list:

1. Ok disconnect the battery ground wire

2. Here is where the screwey-ness begins. There are only three wires in the alternator plug- 26 black/red has a ring terminal that gets attached to chassis with the bottom regulator attaching screw. That's the ground. Wire 38 black goes to battery + (that's B+). The last wire #35 Orange which goes to the regulator F (field) terminal. There is no ST or stator wire.

3-8 Ok

9.  The yellow wire from the plug in #8 is connected to alternator B+. It doesn't say to connect wire 38 black in #2 there also, perhaps that will come later.

10. Connect white/black from plug in #8 to stator tap on alternator- Ok.

11. There is no ST wire, so there is nothing to tape.

12.  "Connect FLD wire to NEW green/red wire in kit". That instructs to connect 35 orange (from #2 ) to the green/red wire from their plug in #8.

13. Now connect 38 black B+ wire to alternator B+ (I mentioned that in #9)

14. Connect ground 26 black/with red stripe to chassis at bottom regulator attaching screw. The radio suppression capacitor is also attached with the same screw.

15. OK. 

Now FYI, wire 904 green/red stripe goes into regulator plug S (stator). This same wire goes several other places- it comes from ignition switch C which is on in start and run. It connects to the infamous pink resistor wire there (but that's another story), goes to the firewall plug, where it connects to 640 r/y that goes up to the dash printed circuit, and from the firewall plug it goes through to the engine compartment and over to the regulator S terminal. So PA's pseudo external regulator does have B+ supplied to it via wire 904 with the ignition in the run and start positions. You may want to check for 12v there in those conditions.

I have seen pictures of the inside of the PA's external "regulator" and no it isn't a regulator but has several components that requires its use to make their alternator operate. I think it has several diodes and resistors, but not much

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Thanks a lot for the info -- I appreciate the detail!  I will go through my wiring again, but some voltage measurements:

The F on the voltage regulator, connected to the alternator green/red wire is at 8.6V when the car is running.
The S on the voltage regulator is a solid 12.5V (fyi, no pink wire, long ago removed)
 
the output of the Alternator (if I measure the voltage at the battery posts) is around 12.4-12.8V.  Seems to move around a bit, but it's not enough to charge my battery.  I have no electric fans, or A/C, or stereo.  
 
Is the Field voltage from the voltage regulator high enough?  It seems like 8.6V is a bit low.  I'll check my wiring again, but PA performance has agreed that 8.6V isn't enough to turn on the alternator.  I must say, I'm impressed with PA Performance's support line so far...very responsive!  
 
edit: quick update: I did not connect 38BK to b+ (your step 13, above), as per your note #1.  I've got a fuseable link for note #2 coming, but I didn't think this would effect anything, would it? (electrically, is it needed with the big 4GA wire connecting starter solenoid post to B+ on alternator?)

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1 hour ago, Flanders said:

edit: quick update: I did not connect 38BK to b+ (your step 13, above), as per your note #1.  I've got a fuseable link for note #2 coming, but I didn't think this would effect anything, would it? (electrically, is it needed with the big 4GA wire connecting starter solenoid post to B+ on alternator?)

No a fuse link should not affect the output as long as its big enough to carry the current and all connections are tight. The size of the wire going from the alternator to the starter solenoid post has to be big enough to carry the current. That is dependent on the size of the alternator- ask PA Performance how big it should be, but it will be much larger than anything in the stock harness. How much voltage does PA say should be on F? What do you have on A? It should be 12v or higher when charging.

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I just unplugged the connector at the voltage regulator, and started up the car.  When measuring the voltage at the connector (not at the regulator):
 
Battery+ post: 12.31V
F: 0.02V  (not quite zero)
S: 12.11V
A: 12.25V
 
When car is off, and the key is in the accessory position (note I had the charger on the battery for 20 minutes, so it brought the voltage up a touch):
Battery+ post: 13.11V
F: 0
S: 12.9V
A: 13.11V
 
I'm only seeing 8.6V on the Field output of regulator, but I should be seeing 0.5V-1V less than battery+ post (12V+).
 
PA has given me a few more measurements/suggestions.  The voltage on the S + A of the voltage regulator plug seem to be ok.

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Since only PA knows what their pseudo regulator is doing, they are the only ones who can advise you, but it seems to me that their regulator and perhaps the alternator need replacing. All measurements show low voltage at F, but A and S are OK.

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yeah, the plot thickens -- when I disconnect the plug on the back of the alternator and measure the voltage at the green/red prong, I get 11.9V (battery is 12.4).  So this should be enough field voltage to get the alternator working.  If I was to wager a guess, my alternator is pooched somehow.

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