[Roadsters] Another electrical question

[John F Sandhoff]

> Now, as to the "S/Brake" business.  I am a low-winshield
> guy, and have never worked on a '70 model...

I'll chime in here. It's been at least a couple of years since the
s/brake light has been a topic :-)

First, John, clever way to add the charge light. For those not in the
know, most "single wire" alternators actually have a connection that
can be connected thru a dash light and indicate if the alternator
is working. Yes, the traditional "idiot light". As I understand it,
for those of you that have to "blip" the throttle to get the one-wire
to start up, adding this light may alleviate that issue.

But I digress...

The s/brake light, on post-67 cars, is part of the dual-circuit
hydraulic brake system. There's a differential valve on the firewall
that both of the dual-master fluid circuits feed thru. If there is
unequal pressure between the two sides - meaning one side has a leak
or is out of fluid or otherwise isn't holding pressure - this switch
turns on the red "S" dash lamp. If that lamp goes on when you hit the
brakes, it means you don't have all your brakes!

It's always good to know that the lamp hasn't burned out (and hopefully
not from overuse). "Modern" cars will turn on all the idiot, err,
warning lights briefly, but for our Roadsters the brake warning light
was an afterthought brought on by the US DOT. So... Nissan added the
"s/brake" switch. All this switch does is... turn on the lamp!

-- John
     John F Sandhoff sandhoff at csus.edu  Sacramento, CA