TR2/3/3A Interpreting fuel pump safety switch wiring diagram

[GTP1960]

I,m going to install this safety switch tomorrow (I hope).
not sure what the best terminal is for a few of the wires. ( see attached instructions)
i plan to connect the green "tach " wire to my coil, neg. side.: to send an "engine running " signal.
one purple lead goes to the electric fuel pump.
black to ground

the others I am not sure of:
red goes to switched 12v (interpretation?/ suggestions?)
second purple goes to switched 12v or battery (same question?)

is "switched 12v" referring to the starter? Ignition switch? Something else?
any wiring suggestions appreciated, as I am kind of over my head with electrical.

thx & best regards,

 

[TR3driver]

So you've converted to negative ground, correct? "Switched" 12v refers to the ignition switch, that is, a source that is only hot when the ignition is on. On a TR3A, you could grab it from the coil hot terminal if you want, or from either the white or green wire terminal at the fuse block.

Your controller has the equivalent of a relay inside, so the red wire provides power to the electronics while the purple wire provides power to the pump. So the purple can be either switched or unswitched without draining the battery with the key off. My preference would be unswitched, so the ignition switch doesn't have to carry the added load of the pump. But it's probably no big deal either way.

 

[GTP1960]

So you've converted to negative ground, correct? "Switched" 12v refers to the ignition switch, that is, a source that is only hot when the ignition is on. On a TR3A, you could grab it from the coil hot terminal if you want, or from either the white or green wire terminal at the fuse block.

Your controller has the equivalent of a relay inside, so the red wire provides power to the electronics while the purple wire provides power to the pump. So the purple can be either switched or unswitched without draining the battery with the key off. My preference would be unswitched, so the ignition switch doesn't have to carry the added load of the pump. But it's probably no big deal either way.

Randall,
thx for reply.

yes it's neg. ground.
so I should run the red to "the coil hot terminal, or from either the white or green wire terminal at the fuse block" ( I'll probably run it to the coil + side, as I plan to upgrade my fuse box sometime soon anyway.....see anything wrong w/ that?)

and I should run the 2nd purple to unswitched ....? (So what is the optimal unswitched terminal?)

thx again

 

[TR3driver]

"Optimal" is probably the A1 terminal on the control box, or the hot terminal on either the ignition switch or the main headlight switch (which are both connected directly to A1). That way, the ammeter will still be between the pump and battery and so will indicate if the pump is drawing current from the battery (rather than from the generator). But again, it doesn't matter all that much, as the pump only draws about 1.5 amps average (according to Facet) which isn't enough to even show reliably on the ammeter. I doubt you would notice the difference if you went to a brown wire at the fuse block or starter solenoid.

You might want to consider a fuse, though. Maybe wait and wire the pump along with your new fuse box?