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Re: Looks like alternator failure--opinions solicited

To: "Max Heim" <max_heim@sbcglobal.net>, "MG List" <mgs@autox.team.net>
Subject: Re: Looks like alternator failure--opinions solicited
From: "Paul Hunt" <paul.hunt1@blueyonder.co.uk>
Date: Sun, 1 Jan 2006 15:01:29 -0000
First thing is to measure the voltage at the brown wire at the fusebox and
compare that to the brown at the alternator, could simply be a disconnection
between alternator and solenoid.  With a charged battery and minimal
electrical load you should see about 14.5v on both.  As the electrical load
is increased you will see the voltage falling - with the original factory
alternators at least, many aftermarket units are much higher output and
suffer less - and how much the voltage differs between fusebox and
alternator is an indication of how good your connections are.  With no
charge and a good battery I'd expect to see about 12.5v with minimal
electrical load, lower as load is added.   However I'd have said that the
overdrive would have been one of the last things to be affected, unless *it*
has bad connections entirely unconnected with the alternator problem,
although I only have experience of the later LH-type, I assume you have the
earlier D-type.

First the warning light staying on, then going out but apparently losing
voltage i.e. running off the battery, implies a progressive failure to me.
Could be nothing more than the connector working loose, or something
internal which could be voltage regulator, brushes/slip-rings, diodes,
windings etc.  Whilst I have changed a diode pack in the past unless the
symptoms are clear you could be chasing two or three faults, which gets
frustrating.

PaulH.

----- Original Message ----- 
> Several days ago, I noticed the alternator warning light
> stayed on for maybe a minute after startup, then went off. Later that day,
> headlights seemed to be dimmer than normal...




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