Corey, I'm not a TR6 expert but I am pretty good at electrical, so I'll have
a shot at it.
> What confuses me is that the round metal plug is a 6 spade
> connector switch (with 5 positions)
So what you're saying is that 2 of the 6 connectors are obviously connected
together on the back of the switch, right ?
> obviously not the early switch (68-72) which had 4
> spades. I looked at your book and Moss Motors to compare switches, but
> couldnt find it mine looks like #30, but has 6 spades.
I'm guessing this would be a later replacement switch then. Should work
fine if you can figure out the right connections to it.
I'd start by doing some tests on the switch with an ohmmeter. (If you don't
have an ohmmeter or DVM, get one. A suitable DVM can be had from Horrible
Freight for under $10, an excellent investment IMO. I keep one in each of
my LBCs, plus one on the workbench.)
With the switch installed on the lock mechanism, for each position of the
key, find out which terminals are connected together. Make a little chart,
something like :
ACC 1-2
OFF 1-4
RUN 1-2-3
START 1-3-5
Obviously those numbers won't be right, the chart is just an example.
Now look at the color codes on the wires. According to Dan's 71 TR6
schematic, you should have multiple white wires, multiple brown/white wires,
and a white/red wire. If that's not what you see, you'll need to
investigate further ... post here what you see & we'll help you.
The brown/white wires should be connected together (if there's more than one
of them). This is the power to the switch and goes to one of the terminals
that is involved in the RUN, START and ACC position connections (if you have
an ACC position, of course, I don't know if a 71 TR6 does). In the example
above, this would be terminal 1. If you have two brown/white wires, they'll
need to go on the two terminals that are connected together externally.
The white wires are the power from the switch to the rest of the car
(including the top of the fuse block). They'll need to go to terminals that
are involved in the RUN and START positions.
The white/red is the power to the starter solenoid, it goes to the terminal
that is only connected in the START position.
> The loose
> wire successfully started the car when connected to either
> position 4 or 5,
> but the fuse box gets dangerously hot.
Note that this does NOT indicate a problem with the ignition switch. You've
either got a marginal connection at the fuse block, or something farther
down is drawing too much current.
Does it still get hot with the fuse removed ? If so, you've eliminated the
fuse itself as the bad connection (it does happen), and everything that is
powered through the fuse. That leaves either a bad connection between one
of the wires and the fuse block, or something drawing too much current. The
only other candidate for too much current is the ignition coil, so turn the
engine until the points are closed, disconnect the coil's white wire from
the fuse block and measure resistance from the wire to ground. You should
see roughly 3 ohms here. If it's 1-2 ohms you've probably got the wrong
coil (later TR6 took a lower resistance coil). If it's under 1 ohm, then
either the coil or the wire is shorted. In that case, remove the white wire
from the coil & repeat the test. If the coil is shorted, the only cure is a
new one.
Randall
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