kevinod

Hi guys,

late 79 (80 model?) 928, 4.5 manual.

I'm replacing my alternator with a Bosch AL325X (thanks Roger!) and struggling to work out the connections. Been searching all over the place on loads of different forums but can't find the answer I need.

Long story short, it was someone else who took the old alternator off, and I no longer have it. So I don't know how the old one looked or was wired.

Anyway, I have 3 wires coming from the car



one of which has continuity to the starting post in the engine bay. I'll hold my hands up and admit I don't know much about alternators but I am reading up and trying to learn. The other 2 connectors would be - one live when ignition is on, and one to the back of the dash to go through the bulb, right?

Here's a pic of the alternator -





I'm thinking the top left connector with the big nut on it will go to the battery (positive of course), since the plastic part has a + on it :-) so the $64,000 question is where do the other 2 connectors go.

Could anyone shed some light on it for me?

Kev

Alan

Boy thats dirty in there - The two big rings go on the same post - the big one

The small ring goes on the small post.

There are only 2 connections really Porsche just happens to connect two together on the alternator stud, these are 2 red wires (that now look more brown due to heat and chemicals).
These are the B+ wires - one to the starter and one to the jump post.

The other is the 61 wire to the bulb & resistor in the pod the other side of the bulb/Rx is ignition (15) - it doesn't go to the alternator.

Alan

kevinod

Thanks Alan! Just using 2 alt connections matches what an automotive electronics book has in its diagrams so makes more sense now. I didn't know enough to be sure it was the same setup on this one. I'll hook those up and hopefully it'll all start for me! :-)

j.kenzie@sbcglobal.net

Sorry to bring up an older thread. But Alan, isn't the smaller wire supposed to connect somewhere on the alternator to excite it or something? I swear my old original alternator (long gone) had two big red wires, and a smaller wire. I have ordered this alternator for my 84. Do I just connect the big red wires and leave the small (green?) wire dangling?
Thanks again,
Dave
PS
I see you say "the small ring goes to the small post" so I think I misunderstood. I would ask however, which post? And what does it mean that the other wire doesn't go to the alternator. Which wire does and which wire doesn't? Sorry to be dense.
Thanks,
Dave

Alan

The ignition (15) doesn't go to the alternator just the (61) small wire that was shown. It goes to the post usually labeled D+. The main post is usually labelled B+.

On some German alternators you may also see (61) and (30) for D+ and B+ respectively.

On re-reading what I wrote it does seem a bit confusing...

Alan

j.kenzie@sbcglobal.net

Thanks a million, Alan.
Dave

Mrmerlin

and to be clear on the picture posted ,
the 2 thick wires go to the + stud at the 1030 clock position,

the blue wire goes to the insulated stud holding the diode board at the 530 position

depami

And, for all you visual people .....

Mrmerlin

Denny your pretty handy with that computer of yours,
I am glad your here to make a difference!

depami

Thanks Mrmerlin,

I’m always in the background making snide remarks while sucking in technical offerings from the likes of you and others.

I don’t really have much 928 knowledge to share so hopefully I can occasionally help someone by merely rewording the wisdom of those that do.

Todd Gibbs

Sorry to drag up this old thread, but I think its useful information for others + with my new question.

Im trying to connect up my 1979 alternator. I have 3 connections on the alternator and 3 wires on the loom. One is easy since its smaller. The other two are more difficult.

I have plugged the brown/red wire into the B+ terminal and the green/black (maybe blue) into the D+ terminal... that leaves the other wire to go into the middle terminal.

Does anyone know if that is correct ?

Thanks in advance!
Todd.