In a message dated 97-11-07 22:05:30 EST, mxgo@ix.netcom.com writes:
> In looking at the wiring to the lucas alternator, I have the following:
>
> 1. At the 3:00 o'clock position I have the plastic plug with three wires,
> at the fartherest most point (from the center of
> the alternator) there is a brown/yellow wire, second toward the center,
> there is a large brown wire, and the third wire is
> also another large brown wire.
>
> 2. At the 6:00 o'clock position there is the small brown.
>
> I know one of the large brown wire goes to the starter. My question is
what
> is the function of the second large brown wire
> and if you wish to use an GM alternator, where do you connect this second
> large brown?
>
> I have read the information given in the VTR pages dealing with
alternators.
Martin:
It appears that your car has been modified. Evidently, this is a common
modification, because my ''71 was modified in a similar manner by the PO.
There was a second large wire going to the Battery in my case (electrically
the same as going to the starter). I know for a fact that this was a PO mod,
because the wire went about a foot, where the insulation had been stripped
off about two inches, the bare wire inserted into a ring terminal on a red
wire, twisted a few times, and taped. No crimp, no solder - just a few
twists!
If you have a large wire running from the alternator to the starter, it is
redundant, and should be removed. This extra wire bypasses the ammeter, and
will cause the ammeter to give a much lower reading than it should. The main
feed from the alternator should go to the ammeter, and from the ammeter,
another large wire should go to the starter. The large wire from the ammeter
to the alternator should be Brown/White, but sometimes the colors fade, and
it is hard to see the white stripe. The large wire from the ammeter to the
starter should be Brown.
The small brown wire should be coming from the starter, and goes to the fuse
box as well as to the alternator (on a '73, the three wires are spliced
together in the harness - one from the starter, one from the alternator, and
one from the fuse box. On a '69 -'72, the wires are connected together at a
junction box on the inner fender, near the fuse box.). The Brown/yellow wire
comes from the "alt" warning light.
Since your car is not wired per the factory manuals, it is difficult to
provide advice from here, but the first thing I would advise is to verify
that the large wires are connected as stated above. If so, discard the wire
to the starter, and connect the wire from the ammeter to the screw terminal
on the GM unit. When you verify the connections, be sure to disconnect both
ends of the wires to prevent a false reading.
If you can't determine where the wires go with certainty, the safest thing to
do, to convert to a GM unit, is to connect the two large wires together,
insulate the connections well, and tie the wires back in a safe location.
Then, run another large wire from the screw terminal to the starter. This
wire should be at least 10 Ga, but 8 Ga is prefered. This will provide you
with the correct charging configuration, but the ammeter will read only
discharge (the discharge reading is no longer related to the charge/discharge
status of the battery, but will instead indicate the electrical consumption
of the car's electrical system). The small brown wire should be tested to
ensure that it has power on it at all times, key on or off. If so, connect it
to terminal 2. If not, isolate it and connect a jumper from the screw
terminal to terminal 2. Connect the brown/yellow wire to terminal 1.
I hope this is of help, and is not too confusing. If you have any other
questions, please call on me, and I will do my best to answer them.
Dan Masters,
Alcoa, TN
'71 TR6---------3000mile/year driver, fully restored
'71 TR6---------undergoing full restoration and Ford 5.0 V8 insertion - see:
http://www.sky.net/~boballen/mg/Masters/
'74 MGBGT---3000mile/year driver, original condition
'68 MGBGT---organ donor for the '74
|