Argh!
What is the correct manner in which to hook up a pair of fog
lamps on a TR3? My original idea was to take the hot off the
ignition switch; put an in-line fuse between the ignition and
switch; then wire the two lamps in series; grounding at the
end.
Ack! No! That poor little ignition switch was never deisgned to take
the load of lamps.
Decide what functionality you want. Then go look at
www.dimebank.com/Light-Up.html.
In general, I recommend that people rig fog lamps to be on in parallel
to the parking lamps (so you can drive down the very foggy road with
just tail lights and fog lamps, essentially) and driving lamps in
parallel with the high beams, only. Unless you're running something
like the Marchal "radar" driving lights, which do well both as fogs and
drivings, you won't want to run them together, or the driving lamp
alone.
I'd recommend two nice SPST toggle (or pull, since this is a TR3)
switches in the dash, each leading to the coil of an individual relay.
The relays get *fused* 12V going to the source of the load side; since
you won't run them together, you can use the same fuse to supply both
relays (even if you were going to run them together, a single Lucas 35A
fuse is enough).
Supply the fog lamp switch with power from a red lead, perhaps from the
dash lamps or direct from the headlamp switch. Supply the driving lamp
switch with power from a blue/white lead, perhaps from the high beam
indicator.
While you're at it, I *highly* recommend that you put a relay on the
original headlamps. Fuse, too. I've seen too many melted harnesses from
cars that got a short somewhere in the lamp circuits.
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