In a message dated 98-12-10 10:26:46 EST, shmitty99@hotmail.com writes:
> BUT I also noticed that my
> ignition light was out. I seem to remember seeing it burn when you turn
> the ignition on. Now it does not. The high beam light works and I
> really don't have a way of testing the brake light. The reason this
> bothers me is that I remember Dan Masters saying that if the ignition
> light was burnt your charging system will not work.
Ryan,
Without the ignition light, there is a 'slim' chance the alternator will work,
but it's iffy at best. To provide a charge, the alternator needs a current
through the field coil. Until the alternator is charging, the only source for
this field current is from the battery via the warning light. After the
alternator is up to speed and charging, there is an additional set of diodes
in the alternator that supply the field current.
The field current is needed to create the magnetic field, which couples to the
armature to produce electricity. Sometimes, the iron core in the alternator
can become magnetized, in the same manner as a screwdriver or a pair of pliers
becomes magnetized in your workshop. If the magnetism is strong enough, the
alternator can produce a small amount of current, which is fed to the field
coil, increasing the magnetism, which increases the output, which .....etc,
etc. This is not dependable, as the core can lose magnetism just as easily as
it can pick it up.
I have an article describing the workings of an alternator on the VTR web
site, which I think will help to clarify this. I'm not at home, so I don't
have the URL, but you can start at www.vtr.org, and page down through the
maintenance pages till you get to it.
There are other ways of doing this, so not all cars have a warning light, but
if that's the way the manufacturer designed it (and Triumph did), then the
lamp is neccessary.
There is an easy way to test the lamp to see if the bulb is out, or if the
wiring is wrong or the alternator is defective. Disconnect the plug from your
alternator, and ground the brown/yellow wire (if you have more than one
brown/yellow wire, ground any one of them, as they are all connected together
in the harness). With the brown/yellow wire grounded, turn on the key. If the
lamp lights, then your problem is inside the alternator or the alternator
plug. If not, the bulb is out or there is a bad connection somewhere.
Dan Masters,
Woodstock, Ga for few days (spoiling my grandson again!)
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