[s-cars] More Yosemite notes

[Keith Maddock]

Gabriel Caldwell <gabriel at ts.bc.ca> wrote:
> On another note, it was raining all the way from Vancouver to Redding,
> CA or so.  A couple of times the car hydroplaned briefly and the cruise
> control turned off.  Is this a feature?  i.e. the car could not maintain
> the set speed and turned the cruise control off?

My best guess is that instead of hydroplaning, the water was actually
dragging the speed of one or two wheels down.  This feels alot like
hyrdoplaning.  This can cause ABS to "go active" or "go alert"  due to
the wheel slip.  (some ABS systems have the capability to go active
without a brake switch, as a failsafe against a failed brake switch).
In most vehicles, there is a connection from the ABS computer to the
vehicle communications bus that informs the other modules when the ABS
has gone active.

Some vehicle manufacturers then choose to use that information to
disable cruise control if they know that ABS (and/or Traction Control
and/or ESP/DSC) has gone active/alert. And some choose to have the
cruise control remain enabled.
(which can be really fun to test if you're a traction control engineer,
"look ma, no hands!"...)

Cheers,
Keith
93 S4 (mit ABS) Miss Piggy
90 MX5 (ohne ABS) The Anti-Piggy (DTTTB)
1/7 89 Golf GTI (ohne ABS)  (DRT CCar)
1/7 90 Golf G60 (mit ABS)   (DRT CCCar)