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<x-charset iso-8859-1>Heres the electrical FAQ... for all to read. It covers the early ignitions
switches and what to do with them.
Keith
Electrical theory for your VW. there are no ghosts in there!
By Keith Park
Who hasn't had an electrical problem with their VW? Not many because
as our systems get older moisture and salt take their toll on the connectors
and the brass gets brittle with age and can break.
Ill keep this brief as all you need to know is stated in Ohm's law:
V=I*R
Resistance multiplied by current equals Voltage. Therefore voltage divided
by current is resistance and current equals voltage divided by resistance.
There is one other piece of theory to memorize. current flows THROUGH a
conductor or wire and voltage is the potential ACROSS it (between the wire
and ground). In other words voltage is the energy between the conductor and
ground that pushes the current through. For example 6 amps is the amount of
electricity flowing through a wire and 12 volts is the amount of energy
across it to allow it to flow.
Why is everyone whining about the old 6Volt systems?? Because when the
connections are made or patched improperly or are simply old and dirty there
is less voltage to push the current through and according to ohms law there
is twice the current than a 12 volt system uses to run the same things.
If a connector for a 10 amp 12 volt wiper motor develops a resistance of .2
ohm because it's dirty it will have a voltage drop across it of 2 volts.
This will slow the wipers a little but on a 6 volt system the current
required for the same wiper motor will be 20 amps and the .2 ohm dirty
connection will have a drop of 4 volts and with only 6 to begin with will
bring the wipers to a stop. So, simply put, the 6 volt systems require you
to keep everything up to spec more than the 12 volt systems do, they wont
let you get away with sloppy connections.
Volt-a-drops, these are simple power resistors that are used in series
with the 6V part. They are fine if the part only uses a steady current and
you have a lot of extra power to throw away. Since it's a fixed resistor
and according to ohms law if the current drawn by the device changes so does
the voltage drop across the resistor and therefore the voltage across the
device, say, for instance, a wiper motor which draws different currents at
different speeds and different loads. This doesn't work very well and in
order to get a voltage drop of 6V across the resistor you need a resistance
equal to that of the device being used which the same as connecting 2 of
these devices up, not a very good idea with the limited power output of our
generators. There are DC-DC converters out on the market that convert much
more efficiently but they are very expensive for the larger current models.
Generator to Alternator conversion. This is a good idea but not
usually necessary. The Alternator produces AC as opposed to the generators
DC output. Alternators all have the AC rectified to DC before it reaches
the output terminal because all cars use DC. Alternators are much more
efficient and tend to hold up better at slower speeds where generators fall
apart but if you convert be sure to use an alternator with a large enough
output to make it worth while. Our generators output 30A so you will want
an alternator of say 50A or more. This is only really necessary if you're
running all kinds of lights and a 1000W sound system or something like that.
On my Square I have halogen fog lights, power windows, a good sound system,
and other electrical goodies all over it and I still run a generator and
have no problems. I get 20K out of the generator brushes and 9 years out of
the last battery so I won't convert and most people don't need to.
Grounds! This is the culprit of most of the "Strange" electrical
problems. If a ground connection is off or a high resistance the current
will look for the next path of least resistance and that may be through some
other electrical part that isn't even supposed to be on at the time. You
can find a ground path through a lightbulb and the current flowing through
the bulb will light it, perhaps only dimly, and send you looking for another
problem somewhere. A major offender in the type 3 is the fuel gauge cluster
on the older cars. They are only grounded through the spring clips and that
is just not reliable. When the gauge ground opens up all kinds of weird
things start to happen when the power looks for other paths to ground
through the fuel gauge and other warning lights. The early fuel injection
grounds on the heads were also nasty salt exposed culprits. So, when you are
looking for that strange problem that seems to be affecting multiple things
make sure everything is grounded. On the VW's ground wires are always brown
so make sure everything brown is grounded. Check with an ohmmeter.
What to do about those nasty pre-68 ignition switches. If yours still
works it wont for long and the availability of new ones is almost
non-existent. They were under designed and the 6V ones all took a real
beating switching the 60A or so the 6V solenoids took. The repair is a
relay, a relay being a set of high-current contacts that are operated by a
magnetic coil that draws very little current. Connecting that coil between
the switched output terminal for the starter (Terminal 50) on the ignition
switch and ground energizes that coil every time the starter is selected and
it only draws a half amp or so, so the contacts will last forever. Connect
the high current contacts of the relay between Terminal 30 ( or any B+ high
current feed) and the wire feeding the starter solenoid. The relay will
then handle the current switching for the solenoid. If your switch is still
working now do this and it will stay that way, if its not it may be
rebuildable but when rebuilt, depending on how bad the damage was, it may
not be able to properly switch the high current and require this relay.
This just touches on a couple common problems with the type3's. Keep in
mind that VW was very good at using the same color wires for the same
circuits over the years as well as the same terminal numbers. If the wiring
diagram for your year is black and white then look at another year that is
color and you can figure out most of the colors used in the B&W versions.
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