Alternator Connection Help Needed

[Dave Taylor]

I just bought a rebuilt Bosch and an external regulator to replace my old units on my '74 911 because I was only getting 12.54 volts at the battery and couldn't keep it charged.

I labeled the wires as I removed them from the old alternator and here's the list:

B+ (2 red wires, one large, one small)
D+ (small blue wire)
DF (small black wire, quick connect)
D- (2 small brown wires, quick connect)

The DF and D- wires actually connect to the same place at the bottom of the old alternator.

The rebuilt Bosch has the following connections on the back:

B+ (post)
B+ (post)
D- (post)
D- (post)
+61 (post)
DF (quick connect)

So I can connect my labeled B+ wire and connect my labeled DF wire.
Should I connect the D- to the D- post even though they were together on the old alternator?

That leaves me with the D+ (small blue wire) and I don't know where to connect it. I did a search and read lots of posts and am getting the idea that the D+ on my old unit might be the same as the +61 on the new alternator.

Anyone know for sure? I wouldn't want to make a mistake and wire it wrong. I can post pics if that will help.

Thanks, Dave

[Dave Taylor]

bump...

[Dave Taylor]

[Dave Taylor]

Surely there has to be somebody out there that's solved this problem......help me...help!!!

[Dave Taylor]

bump...

[Early_S_Man]

Dave,

That is a rebuilt 70 Amp [980 Watt] Motorola/SEV Marchal alternator, not a Bosch! Your fan housing will need to be machined 9.3 mm deeper to accept the larger alternator, or you will need to get a '75 or later housing.

You need to wire the two brown wires to case ground studs labeled D-, and the blue or green-faded wire to the D+/61 terminal. The warning lamp lead is usually labeled D+/61 on most schematics ... as in the following excerpt:

[Early_S_Man]

[Dave Taylor]

Thanks Warren!

I think I'll keep the alternator and have someone machine the housing so it fits properly. Thanks for the wiring diagram, too!

Dave