I doing some final wiring before being ready to crank up my T. One wiring project, in addition to wiring up the instrument panel, is hooking up the brake light switch. My brake light switch is the one that attaches to the two middle screws of the transmission door. It has a button that is centered over the brake pedal shaft where it comes out of the transmission, which when pressed depresses the switch button that causes the brake light to engage. It has two terminals. One for that brake light wire and one for the power.
I have a long wire that goes fron one of the terminals on the brake light switch back to the tail light and I need to supply power to the other terminal which I will be supplying with a wire from one of the screws on the terminal block under the hood.
Which screw on the terminal block will be the best for suppying the power to the brake light? I figured that hooking it up to the battery terminal would provide too much juice, so I didn't use that one. Would the same screw that the horn is hooked up to be a good auxillary power supply with which to supply power to the brake light? Jim Patrick
I would go right from the battery terminal, or directly from the battery ,
you can install a "self resetting fuse"in series
that will break the circuit if there is a short,
for about $10,
this will protect againts burning the wireing harness
mine is done this way, with no problems
Having worked professionally with electrical engineering for well over twenty years, I can tell you that connecting direct to the battery is fine. Having said that, I would go to the terminal block. (Just a personal preference.) Two choices. The "always hot" from the battery, makes it easier to check to see if the brake light is working anytime it is convenient to check it. Or the "key is turned on hot" such as the battery to ignition terminal, won't let the brake light switch misadjustment or beakage turn on the light and drain your battery when you're not looking.
And definitely, put some adequate type of fuse to everything except the starter (and even it would be a good idea, but difficult/expensive/unreliable and nobody does it and it never seems to cause a problem). Other wiring often does cause problems and fires that are easily preventable by a simple $5 fuse holder and 20 amp auto type fuse mounted directly from the battery to everything except the starter. Actually, even a 10 amp would probably be okay, and I usually use 15 amp because we had to balance the fuses on systems and I ended up with a bunch of 15 amp fuses.
Drive safely, W2
the terminal block is a good idea, going through the switch is another good idea,
however depending on the load existing on the original conductor that feeds he terminal block,
and taking into account the awg size of this conductor,the age of the insulation on it, and the type of light(s) you will use etc,
as well the original switches . are not designed for the additional load , the contact point may heat up and seperate,
you can save a lot of trouble in the sysetm by keeping it seperate,