cruise control

[treed2@u.washington.edu (T. Reed)]

Hey,

An update - I went to the junkyard today and picked up several different
linkage setups that I will probably use to create a 16v frankenlinkage..
I also got a pair of electrical vacuum switches for the brake and clutch -
I plan on hooking these up per the bentley but after looking over the
electrical diagrams I have a new problem; the circuit described for the
cruise switches doesn't make sense!

There is of course the brake light switch that is normally open (that is,
when there is no foot on the pedal, it is open.. it closes when you step
on the pedal and the lights go on).

Then there are the two electrical switches for the brake and clutch for
the cruise system. These are normally closed (i tested them with a
meter).. so when you step on the pedal they open up (shutting off the
cruise).

The Bentley shows power coming in through the brake light fuse, through
the brake light switch, then splitting. One direction goes to the brake
lights then ground (like any car), the other direction goes through the
two normally closed cruise brake/clutch switches then to the cruise
computer.

My problem with this is that it puts the two brake switches in series.
Because they are different types of switches; one is normally open,
one is normally closed, when you step on the pedal they will reverse
positions (the closed one will open and the open one will close). Having
two such switches triggered by the same mechanical activity (stepping on
the pedal) in series means that current will never flow through both at
the same time.. so what was the point of having the switches at all?

The only possible case I can think of is that the engineers are relying on
the switches being precisely adjusted so that one triggers before the
other and a short duration pulse (pulse length depending on how fast you
jam the pedal) gets through to the cruise computer. That would be
incredibly stupid.

What I want is someone to either tell me I'm an idiot and I'm totally
misunderstanding these wiring diagrams OR tell me that it is a mistake in
the bentley and the two cruise brake/pedal switches in series with each
other are hooked to the hot side of the brake light switch instead of the
switched side. This would make a LOT more sense, but I don't want to hook
it up that way, going against the wiring diagrams, unless I know for sure.

-Toby

On Thu, 28 Nov 2002, Euroroc II wrote:

> I just pulled out all my cruise stuff.... I'll get back to ya on this soon.
>
> -RGK-
>
> At 02:02 PM 11/28/02 -0800, T. Reed wrote:
> >Hey,
> >
> >Another cruise question for ya - I tested the vacuum pump and actuator
> >and they work.. but I only got one pedal switch (the guy who pulled the
> >system forgot to get the other one)
> >
> >I looked in the bentley electrical diagrams and they appear to show
> >electrical pedal switches. The switch I have is vacuum-only as far as I
> >can tell.. there are no electrical connectors and the switch holds vacuum
> >only when it is depressed (ie. the pedal return spring is pushing the
> >pedal against it).. what's the deal with that?
> >
> >How do I wire it up without electrical switches..?
> >
> >Thanks
> >
> >-Toby
>