Re: Dashlights & Headlights!

[jlandry@domain.elided (John A. Landry)]

"lynx@domain.elided" <lynx@domain.elided> scribbled in the sand:

>   Hopefully someone can help me out. I've got a '69 IH 1200series 4x4 truck.
>recently the dash lights started to flicker slightly at idle. The headlights
>did a little too. The amp gauge would bounce around crazy from side to side.
>However when driving down the road everything seemed fine. This has went on
>for a couple weeks right after a changed the alternator.

Andrew,

Just out of curiosity, why did you change the alternator?  Were you having
specific electrical problems then?

Remember that the amp gauge shows you the amount and direction of current flow
to or from the battery and alternator.  The way it's supposed to be wired (on
my Scout II anyway) it shows whether the alternator is providing more or less
current than the battery to the electrical system.  Yours could be wired
differently.  But in any case, if the amp gauge starts fluctuating wildly,
that would have to mean you have massive swings in whether the alternator or
the battery is providing current to the electrical system.

What could cause this?  Several things I can think of.  For starters, a short
somewhere in either the charging circuit or the main electrical system would
be one.  Such a short would cause either the battery or charging circuit to
temporarily drop out and force the other to pick up the load.  Maybe you
accidentally created a short when you installed the new alternator?  Check all
of the associated wiring carefully.  I could see the lighting being affected
by a short.

Another thought might that the alternator's regulator is defective, but you
replaced that, so it's ruled out.  If it were to allow too much or too little
current to be produced by the alternator, then the amp gauge would fluctuate.
But if your battery is in good condition I wouldn't think the lights would dim
much temporarily, as the battery would pick up the load if the alternator
failed.

Flickering is a good sign of an intermittent connection or short.  You did
good to check the ground connection, but obviously that's not it.  Recheck the
alternator connections.  Recheck anything else you may have moved or touched
when you disturbed the electrical wiring before this all started.

>I also had to buy a new belt because the pulley on the new alternator is a
>different size. Would the size of the pulley mess things up that bad???

The pulley size would not be the cause of something like you describe.  The
pulley diameter should only affect the point at which the alternator "kicks
in" and at what point in produces maximum amperage.  Just make sure your
v-belt is in good condition and very tight... alternators put a surprising
amount of load on a v-belt.  A squealing alternator belt means slippage and
could result in low alternator output, but not flickering of the lighting.

Good luck,

John
------------------------------------------------------------------------
jlandry@domain.elided             |
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