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How to tell if you have a 70 amp system?
#1
Hello,

Midlife is going to be working on getting most of my wiring harnesses back in good shape. One of the things I need to do is to replace my short alternator harness.

Vendors show either a 70 amp or standard harness. Is there a simple way to tell which would be correct? The vert came factory with A/C and power top, no power windows. The current alternator is not factory original, it was replaced several years ago by a PO.

Any guidance would be appreciated.

Thanks,
Scott
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#2
I don't have a 73 Electrical assembly Manual. The 72 manual I have states the 65 Amp alternator was installed on 351CJ vehicles with AC and Heated Back Lite, with or without gauges, if I'm reading the notes properly. Another reference book I have shows the following. 1973 8 cyl. with AC, 42 or 55 or 61 Amp alternator, with gauges takes harness number D3ZZ-14305-E. I have no way to verify the accuracy of the information. It may be a place to start. Figuring this out on my 72 was a nightmare until I figured out due to production changes and build date, my 72 actually required a D3ZZ harness. Please let us know what you find out. Chuck
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#3
c9zx;86197 Wrote:I don't have a 73 Electrical assembly Manual. The 72 manual I have states the 65 Amp alternator was installed on 351CJ vehicles with AC and Heated Back Lite, with or without gauges, if I'm reading the notes properly. Another reference book I have shows the following. 1973 8 cyl. with AC, 42 or 55 or 61 Amp alternator, with gauges takes harness number D3ZZ-14305-E. I have no way to verify the accuracy of the information. It may be a place to start. Figuring this out on my 72 was a nightmare until I figured out due to production changes and build date, my 72 actually required a D3ZZ harness. Please let us know what you find out. Chuck

Thanks for the starting point Chuck. I do have the 73 Electrical shop manual, maybe that's a place that might guide me. The PO added the gauges in the center but I think the ammeter ties somehow into the alternator wiring harness since there were splices all over the place. Seriously I'll bet my underdash and other harnesses had at least 25-30 splices!

Argh!

Scott
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#4
I just replaced my alternator harness and I learned that I have a 70 AMP system. My vert came with factory air, power top and power windows. I do not have the gauges in the center of the dash. I was lucky since I still have the original alternator.

Mike

[Image: 57_23_07_10_12_47_19.jpeg]

White 1973 (351C stroked to 408, 4V, FMX) convertible with blue deluxe interior AC and power windows.

Mike
Irwin Pa (MCA # 52193)
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#5
Monterey;86206 Wrote:
c9zx;86197 Wrote:I don't have a 73 Electrical assembly Manual. The 72 manual I have states the 65 Amp alternator was installed on 351CJ vehicles with AC and Heated Back Lite, with or without gauges, if I'm reading the notes properly. Another reference book I have shows the following. 1973 8 cyl. with AC, 42 or 55 or 61 Amp alternator, with gauges takes harness number D3ZZ-14305-E. I have no way to verify the accuracy of the information. It may be a place to start. Figuring this out on my 72 was a nightmare until I figured out due to production changes and build date, my 72 actually required a D3ZZ harness. Please let us know what you find out. Chuck

Thanks for the starting point Chuck. I do have the 73 Electrical shop manual, maybe that's a place that might guide me. The PO added the gauges in the center but I think the ammeter ties somehow into the alternator wiring harness since there were splices all over the place. Seriously I'll bet my underdash and other harnesses had at least 25-30 splices!

Argh!

Scott
Ammeter joins into the headlight harness only.

Let me check your shorts!
http://midlifeharness.com

[Image: Flamicon2.jpg]


[Image: oldfart.png]
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#6
My 73 Mach 1 has it's original alternator (53,000 miles) and it is a 70 amp model. My car has the rear window defrost and power windows which are high current draw devices which is why it has the higher output alternator. My other 73 Mach 1 has the 55 amp alternator and it does not have those options. I can get a photo of my 70 amp alternator/harness if that would help.

Steve
73 Mach 1 Blue Glow/Argent Q Code C6 Auto
73 Mach 1 Blue Glow/Argent Q Code 4 Speed
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#7
Vertstang and Steve73, If you can post picture it would be very helpful future reference. It is amazing how under documented these (71-73) Mustangs are. Thanks, Chuck
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#8
Here are some photos of my 70 amp alternator and harness:
[Image: 2n1zxow.jpg]
[Image: iqwolx.jpg]
[Image: 2lseczq.jpg]

Steve
73 Mach 1 Blue Glow/Argent Q Code C6 Auto
73 Mach 1 Blue Glow/Argent Q Code 4 Speed
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#9
What part numbers are on that Alt. ? I have never seen a side post alt on a 71-3. Always see connections on the back.
Is it a late 73 ?
Don
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#10
it doesn't cost much to upgrade to a 1 wire alternator and it'll clean up some clutter under the hood elminating an entire harness and replacing it with only 1 8 guage wire from alternator to the terminal block or hot pos on the starter relay.

i got a tough stuff 1 wire for only like 80 dollars and its a life time warranty item.

something to think about!
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