Date:         Wed, 25 Oct 2006 20:49:40 -0400
Reply-To:     Doug Fitz-Randolph <fitzr@SUSCOM-MAINE.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Doug Fitz-Randolph <fitzr@SUSCOM-MAINE.NET>
Subject:      Factory Cruise Control Behavior Query: posting answer to my own
              question
Content-Type: text/plain; charset="us-ascii"

Hi all. Back last month I asked a question (see  below) about what happens
if you engage the cruise control while coasting in neutral. Here is the
answer: the engine revs immediately up to its maximum RPM. I assume this is
limited by the ECU, but I suppose it could also be limited mechanically by
the travel of the throttle or cruise control diaphragm. I don't know for
sure. There is definitely no tachometer input to the cruise control circuit.
I've confirmed this by looking at the Bentley wiring diagram, by physically
examining the wiring in a van. I also tested it out after installing cruise
control in my van - a bit shocking even anticipating what would happen.

For the record, I received 5 responses to my question, only one of which
provided the correct answer. Congratulations to David Milo! Two of the
incorrect answers were self-described speculation, as in "I think it works
like {explanation}". The other two incorrect responses were offered as
nothing less that indisputable fact.

Cheers,
Doug Fitz-Randolph
Freeport, ME

Original question:
Can anyone tell me what the factory cruise control on a manual transmission
Vanagon does when you set your cruising speed when coasting at 60 MPH (or
some highway speed), say down a hill, with the transmission in neutral? I
would guess that when your speed decreases the engine RPM will shoot up as
the cruise control tries to compensate. The cruise control can detect when
you push the clutch in, but it has no way of knowing whether you're in gear
or not, right? Is there a coil/tachometer input to the cruise control ECU
which allows it to limit engine RPM? I don't currently have cruise control
and I'm curious.