Scott & Spot,
To figure out why the lights aren't working takes a step-by-step
approach. You seem to have taken some of them.
First off, learn to use the voltmeter. It's a most handy tool and will
be of great value to you at this chase for the lost electrons. It has
two wires. The gauge measures the voltage passing from one wire to
another through the instrument. Once you figure out which setting to use
(probably 15VDC on your meter) remember to set to that for the voltage
tests you make.
An observation---you said 'short' Generally, what that means is that
a 'hot' wire (or hot something) gets loose and accidentally touches a
'ground', which usually results in a spark and frequently in a 'blown'
fuse. From the context, it sounds to me as though what you are
experiencing is an 'open circuit' in which the electrons aren't getting
to the destination (ground) but aren't getting 'shorted' either. There
is a bad or missing connection somewhere that stops them from making
their intended route.
From here on, everything is actually easier to do than to describe.
Once you have done it, or seen it done, this all makes sense.
Begin at the fuse box. WIth light switch on, one side of the fuse will
have 12 V. The other side of the same fuse should also have 12v. If
not, test the fuse itself with a resistance test (learn about that
later....) or substitute a fuse that you know to be good. If you haven't
already taken off the fuse box, checked and cleaned the back side, do it.
Sooner or late you will need to--might as well do it now and know the
thing is good.
Then you follow down the wire to the light. It's a one-piece wire
from fuse box to the rear fender. Light switch on, fuse in place, poke
one end of meter wire test lead against the wire connector and the other
test lead against an unpainted bolt, bumper bolt, bare spot in the body
metal, boot latch, something. Look at the needle. If it moved to 12,
good. If it moved the other way slightly, just reverse the position of
the two test leads. Essentially, you will either have 12V or 0. If 0,
there's a problem between where you are and where you started. If you
have 12, keep going. Plug in the wire to the light, then use your test
lead inside the light's socket. Test for 12 v on each of the little metal
contacts inside the socket. One should have 12v, the other 0. Test from
the one that has 12v to the outside of the socket. This is now testing
that the socket's ground is OK. If you had 12 when the second lead was
to the body (or something) but you don't have 12 now when second lead is
to the socket body, it tells you that the connection between the socket
itself and the chassis ground is bad or intermittent.
That's where I suspect your problem is. The rubber gaskets dry out
and perish, water gets into the taillights, makes a small amount of rust
or corrosion and causes a large amount of grief as you look for the small
problem. Double check the sockets, the connections and even look at the
base of the lightbulbs. I've seen it happen that the lead tips of the
bulbs don't ....quite..... touch the socket's bottom inside, either
because they have worn away or the socket's spring-pushed bottom is
sticking.
Check through all these little things. Do the same test on the other
light.
About now you will want to learn how to use the Resistance (Ohm)
scale on the meter. That is the scale to help you evaluate the quality
of connections and continuity of a circuit. F'rinstance, you can't see
if the filament in a bulb is broken. Use the resistance scale, put the
test leads onto the lead tip and to the shell of the bulb and look at the
meter. Needle moves way over---it's good. Needle didn't move--try the
other lead tip. Moved-that filament is good, so you know you tested it
right but the bulb is half dead. Maybe someone else can coach you
through that part. You will learn both of these and find them both handy
for getting your tail lights working. Once they're working right, you
should be set for another 20 years.
Bob
. I've cleaned the connectors, fuse box, giggled and wiggled wires
too. It will sometimes just start working again and then stop. I know
it sounds like a short some
> where.
> Something I am missing? Is there a better method of tracking down
> the problem with a volt meter (which I have but don't have a clue how
to
> use!)? It is suppose to be 60 here today! TIA!
>
> Happy Holidays!
>
> Scott and Spot
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