Thanks, Barney.
And yes, you're right I wasn't checking continuity correctly. You pointed
out my stupidity without being offensive; maybe you should have been in
politics :) If I had only thought what the word "continuity" means I could
have figured this out. DUH.
I was checking using the ohm meter and touching the black lead to ground
and the red lead to the end (one end) of the wire at the fuse box end. So I
assume I wasn't checking for anything besides current but using the ohmmeter
scale?
So maybe it was just a bad connection.
One of the many great things about this list is that I can learn as I go
and you all don't charge me $70/hour :-).
Monte 79B, 67B, and 74 1/2 parts car
Kahoka, MO USA
----- Original Message -----
From: "Barney Gaylord" <barneymg@ntsource.com>
To: "MonteMorris" <mmorris@nemr.net>; "MG list" <mgs@autox.team.net>
Sent: Wednesday, June 19, 2002 11:56 PM
Subject: Re: blowing fuses
> At 08:23 PM 6/19/02 -0500, MonteMorris wrote:
> >.... 67B, which had been blowing the bottom fuse as soon as I turned it
> >on. .... take all three green wires off the fuse terminal and plug them
in
> >one at a time to see which one blows the fuse, and/or check
> >continuity. Two of the wires caused the short and both had no continuity
> >when tested. Why would two wires be shorted in this circuit?
>
> Two green wires shorted together and grounded could be a result of a short
> or overload in one circuit that melts the insulation in the wiring harness
> to short the two wires together and to some point on the chassis at the
> same time. But that sort of a short does not usually clear up just by
> moving the wires about.
>
> Not having continuity doesn't sound right. If the two wires are both
> grounded they will abviously have continuity between them. The only way
> they don't have continuity from one end to the other is if they are broken
> or cut, in which case they probably wouldn't work again after just a
little
> fiddling. Or there may be a loose connector somewhere in the middle of
the
> wire run that you are overlooking, but this is not likely to affect both
> wires exactly the same before and after the fiddling. Too many
coiincidences.
>
> Are you sure you are checking continuity correcty? Maybe you should try
> disconnecting both ends of the wire when checking for a short to ground,
as
> a connection to an electric motor can have a very low resistance when the
> motor is not running. Also check for continuity with the meter test leads
> on opposite ends of the same wire. When multiple green wires go through a
> harness it's hard to say which is which where they emerge from the harness
> somewhere else.
>
> >I cleaned the terminals to all the affected accessories
>
> Corroded terminals do not generally cause shorts, but they could have been
> touching something the was grounded before your fiddling. Again, not
> likely to have exactly the same affect any two wires before and after.
>
> >and removed the voltage stabilizer (according to Moss, not supposed to be
> >one on the 67, but there was). I sanded the case of the stablilizer and
> >where it mounts to create a better ground and lowered it where I could
get
> >to it the better the next time.
>
> That could (possibly) have accounted for a short to the body in one green
> wire at the prior mounting location, but probably not affecting two wires.
>
> >This fixed (temporarily?) the problem, although I don't know which one
was
> >the direct cause since I didn't want to blow any more than the 5 fuses
I'd
> >already blown
>
> I have a sneaking suspicion that you have not seen the last of this
> problem. Perhaps it's a bare wire that was cut on the edge of sheet metal
> where it pases through the firewall, and the short is disturbed
> (temporarily) when you move the wire. If it happens again, start over and
> be sure you check the three different green wires individually for short
to
> ground (and not possibly checking the same one twice?). Meanwhile, keep
> some more fuses handy.
>
> Barney Gaylord
> 1958 MGA with an attitude
> http://www,ntsource.com/~barneymg
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