Alternator wiring advice

[Crazy Horse]

OK, I need some wise and experienced advice as I am performing a DIY alternator replacement in a 1979 911 SC.

Below is a pic of the old alternator:



And below is a pic of the new alternator:




When I took the old alternator out, there was a wire hanging loose with a female pin end.

Can anyone tell me the right way to hook the old wires to the new alternator?

Any assistance would be greatly appreciated - THANKS !!!

[Crazy Horse]

bb

['78 SC]

Jack,

I noted the following connections on my '78 (following your 2nd sketch, clockwise):

+61 (blue)
B+ (2 red)
B+ (nothing)
DF (black)
unlabeled (3 brown on single lug) [this is labeled D- in your sketch]
D- (single brown) [this is labeled D in your sketch]


Don't know why your alternator would have different connectors (though your two diagrams appears equivalent). Maybe one of the electrical gurus will comment.

[stevie 77 930]

Jack,

Looks like your old alternator was wired and retro-fitted with an internal regulator. While the new alternator is set up for the external regulator. The male pin connection uses a black wire that goes to the external voltage regulator. This is the wire you saw hanging. The external voltage regulator is located on the connector board on the left side of your engine compartment. The external voltage regulator would have the blue and black wires connected if memory serves me correct. What you need is to get an alternator with the internal regualtor. Otherwise, you are looking at putting a new external voltage regulator in as well and putting it back to the origianal set up. The original wiring is (B+ Red wire) ( 61 blue) ( D- brown) ( male pin Black) Hope this helps

[Crazy Horse]

Thanks for the direction - however, this appears to be the original alternator I am taking out and it was currently working with an external regulator. I know this as the red light came on in my dash and I replaced the external regulator (pin broken) and the light went back off.

The alternator I am removing is marked as follows:
VALCO
14V 75A
A14 N 11
PORSCHE
911 603
120 04
1 1

Any ideas as to this anomolie?

[stevie 77 930]

This alternator requires an external voltage regulator



This does not

[Crazy Horse]

Steve,

I am replacing an alternator exactly like the one in the lower pic with one like the upper pic. I already have a new voltage regulator now and I think all the wires are there too.

I know the blue wire goes on the "61" leg, the black wire "connector" goes in the DF pin and the red wires probably go on the uppermost B+.

I am left with one large brown wire and a set of three brown wires that are together. Do I separate these between D and D-, or do I hook them all up to D-? If I separate the brown wires, which go on D- and which goes on D?

Thanks all for the assistance !!!

[stevie 77 930]

All the brown wires go to D-

[RoninLB]

this is good to keep around.














ps: I didn't need the resistor upgrade to the alternator idiot light with the Valeo internal regulator alternator.

[MZ3 SBC]

So my alternator light was on constant. I removed it to discover the blue wire was connected to the D-1 terminal and the brown grounds were connected to the 61 terminal.

From what I am reading here - that is reverse order?

[MZ3 SBC]

[abdielhiram]

Hi

I am new here, but have weeks looking for some advise on an alternator problem.

My car is a 911SC 82 and I have the 3 Wires alternator. My problem is, the light wont turn on when ignition is set, and of course it wont charge.

My theory is the 61 pin is a negative until the car is started, and then the alternator will start charging? if thats the case, it means I have a problem with the alternator? I have no continuity between the D- and the 61 when the alternator is out. I have tested the blu wire to the cluster and it seems OK the cable. If we connect the blue cable to the D- the bulb turns on but it wont go off when the car is started.

Thanks for your advise.

[Dmitry at Pelican Parts]

Check out the link below to a DIY of alternator replacement. It should help you troubleshoot any issues.

Porsche 911 Alternator Troubleshooting and Replacement | 911 (1965-89) - 930 Turbo (1975-89) | Pelican Parts DIY Maintenance Article


-Dmitry

[MarkWard]

New to me 1980 ROW 911. At some point the alternator was upgraded to an internal regulator style. Black wire was cut short. Blue wire or D+ was not attached and it appears the harness went to an aftermarket external regulator still. I understand how to wire it correctly, but am not 100% sure about the wire studs on this Valeo alternator I removed as part of the broken head stud replacement. I have attached a picture of my Valeo alternator with an internal regulator. Not sure if top will be top. Edit it's not.

Post labeled + is obvious at 6 o'clock and is Battery power. It's not clear, but I believe I see a - minus at the post, 11 o'clock, where the brown ground wires were attached when I removed the alternator. So that should leave only the stud at, 3 o'clock, for the D + or blue wire that I found disconnected. Just want to be sure. The pictures in the Bentley are not quite clear. If someone could clarify I'm understanding correctly. Thank you. Mark

[winders]

https://forums.pelicanparts.com/9567158-post13.html

[MarkWard]

Scott thank you. D- and 61 aren't quite what I would expect for "labels". Grounds should be 31 and the alternator exciter lead should be D+. Hence my confusion. Doesn't really matter as long as I attach them correctly. Thanks again. Mark

[winders]

I am not sure that this bulletin from Porsche could be more clear:

[MarkWard]

It just a letter and numbering convention I'm not familiar with. Page 970-10 shows a diagram and one terminal is listed D+/61 The factory wiring seems to list Grounds as "G" not D- All good. Thanks.