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Re: Alternator light

To: "K. Johnson" <buffymgb@ria.net>, "MG's" <mgs@autox.team.net>
Subject: Re: Alternator light
From: "Paul Tegler " <wizardz@amdyne.net>
Date: Tue, 9 Feb 1999 08:46:21 -0500
if it comes on at idle, you're OK.
Stock Lucas alternatorsr don't start to put out specified voltages
until it reaches 1600 rpm. With fan belt pulley diameters, that's about
1300 rpm engine speed. Most were only rated at 30 amps maximum output.
The later 17 series regulators in the alternator could handle 40-50? amps.
You're headlights alone draw roughly 10 to 25 amps depending on whether
they are stock or halogen.

The idiot light is straped across the BRN and WHTckts of your car. that is
to say,
across the alternator field output (charging source) and the ckt that
supplies
all the 'engine running' accessories items such as fuel pump, ignition coil
,etc.
When the voltage on the running ckt, is higher or lower than the battery
voltage, be it charging or not, that difference in voltage, flows through
the idiot light
to let you know stuff isn't flowing right.

If you have a high resistance some where ( dirty fuse contacts, bad wire
grounding, corroded
engine grounding strap, dirty alternator contacts, or wire connector
contacts) the voltage
drop would light the idiot light.

check all your WHT skt connections, under the bonnet and at the ignition
switch.
Measure the voltage across your battery terminals directly at the battery.
Also measure at the back of the alternator one wire at a time to ground
(engine block),
If they are not the same with the engine running and all assosories off, you
have a bad
contact somewhere.

Paul Tegler
Twin 73' MGB GTs YB and OB
YB born 8/72 (Primrose Yellow) Yellow BGT
OB born 1/73 (Blase Red) Orange BGT
email: wizardz@amdyne.net
http://www.amdyne.net/~ptegler/mgmain.htm
-----Original Message-----
From: K. Johnson <buffymgb@ria.net>
To: MG's <mgs@autox.team.net>
Date: Monday, February 08, 1999 4:42 PM
Subject: Alternator light


>Hope somebody can help me with this...I'm sure it's been gone over before
>but I've missed it.
>
> I have a '70B and the alternator light comes on whenever I turn more than
>one thing on, i.e. headlights and turn signal.  It's dim enough that you
>can't see it during the day, only at night, but gets brighter the more
>things you turn on.  Thinking it was the alternator, I replaced that, but
it
>still does the same thing.  It has a brand new battery in it so it
shouldn't
>be that.  Someone said it was the voltage stabilizer....I'm game for that,
>but I don't know where it's located to check it or replace it.
>
>I'm up for any suggestions...
>TIA
>
>Kathy
>'70B
>'71 Beetle
>'50 GMC P/U
>


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