[Mgs] Fwd: Re: DPO butchering of Alternator replacement?

Charles Hill chillmog at sbcglobal.net
Sat Oct 25 19:05:32 MDT 2014


Here it is.  It went to Simon only as I pushed the wrong button. Didn't 
mean to slight anyone.

Charles Hill


-------- Original Message --------
Subject: 	Re: [Mgs] DPO butchering of Alternator replacement?
Date: 	Sat, 25 Oct 2014 18:39:56 -0500
From: 	Charles Hill <chillmog at sbcglobal.net>
To: 	Simon Matthews <simon.d.matthews at gmail.com>



Simon,
Not much on alternators - my car still has a generator.  Here is a link
to the 71 MGB wiring diagram.
http://chicagolandmgclub.com/techtips/mgb/pdf/mgb_wd06.pdf
It looks like the two brown wires on the original alternator are
connected to the hot terminal on the starter solenoid.  My guess that
the two wires are a hold-over in the car's wiring from the days of
external regulators.  Most alternators now have an internal regulator
and the second smaller brown wire is not necessary.  Keep the small
brown/yellow wire for the charge light.

Charles Hill


On 10/25/2014 6:03 PM, Simon Matthews wrote:
> I have a '71 MGB-GT on which I am replacing the alternator.
>
> According to Moss Motors, the replacement only uses 2 pins of the
> 3-pin connector (the instructions  are badly written, but this is what
> I understand from them).
>
> Looking at the existing installation, I see an alternator that has the
> new 3-pin setup. The wiring on this 3-pin setup has a thick brown wire
> (presumably the Positive wire) connected to one terminal, a medium
> brown wire (presumably the "A" wire) connected to another terminal and
> a thin brown/yellow wire (presumably the Indicator wire: "D")
> connected to the smallest terminal on the Alternator.
>
> Also hanging from the wiring harness is the old 3-pin connector, which
> has one wire still attached -- a thin brown/yellow wire.
>
> Was there ever an alternator in which the connection of these 3 wires
> would have been necessary? Is the connection of the medium brown wire
> just redundant, or could it be harmful?
>
> Any suggestions?


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