Date: Mon, 14 Jun 1999 13:38:21 -0700
Reply-To: "Michael A. Radtke" <m.radtke@ELM.AZ05.BULL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: "Michael A. Radtke" <m.radtke@ELM.AZ05.BULL.COM>
Subject: Re: HOWTO: Audiovox cruise control install experience
Eric,
Thanks for the detailed HOWTO.
I installed a similar unit a while back and it seems to work fine on my '84.
1) Why did you use the magnetic pickup? I thought that was only
necessary with an automatic transmission? My installation senses
engine speed through the coil wire.
2) A disengage down hill is a safety feature. The idea is that the
car shouldn't continue to speed along, or increase speed over some
length of time with that the cruise thinks is a closed throttle. I
haven't experienced it with my current cruise control, but I did
experience it with the previous one on long mountain descents.
3) Just a week ago, I made a wiring change in my installation to
reflect behavior that I was used to in all my previous cruise
control installations. The AudiVox unit acts like most factory
installations in that there is no provision to disengage the cruise
without losing its setting except by using the brakes. All of my
aftermarket units, until the AudioVox, retained the last setting
when switched off and then back on again. Only using the set key,
or turning off the ignition unset the unit.
I measured the current draw of the unit and found it to be less
than 100 milliamps when disengaged, so I reasoned that I could
leave the unit active all the time. So I made the following wiring
modifications.
a) I connected the power to the unit from the control, and
connected directly to the fused power source. This leaves the
unit powered on any time the ignition is on.
b) I disconnected the wire from the unit that senses brake light
battery voltage and connected it to the switched power source
from the control unit. This is the place the cruise unit
power lead was originally connected. This change supplies the
cruise with brake light reference voltage only when the cruise
switch and the ignition switch is on.
c) I added a diode in the wire from the brake lights to the cruise
unit. I don't know whether this was necessary, but with the
ignition or cruise switch off, stepping on the brake pedal
causes this lead to go to 12 volts. With my other
modifications, the brake light reference voltage is zero and bad
things could happen to the cruise. The diode blocks reverse
current flow.
I determined that the current flow was out of the control unit,
so the arrow on the diode should point toward the brake lights
and away from the cruise unit.
With the above modification the cruise acts the same as before, but
will return to its last speed setting if the unit is on and resume
is pressed. It does lose its setting on ignition off.
Thanks again for sharing.
Mike '84 GL '58 Isetta (no cruise)