747 VSS Question

[rr]

Not sure about the speedo cable, I just grabbed the ecm and
ran. I was hoping for an inline unit. Another post by Shannon
squared that away :-( no such luck.

Seems the VSS is a close second to fuel delivery in retro-fit
difficulty. One guy I know took the speedo cable out of the
car, cut a short section out of the housing, made an aluminum
section that held the opto-reflector. A disk on the center cable
quartered black/shiney, and put it back in the car. Works.

BobR.


Bruce Plecan wrote:

> A G20 is a large van, yes?.
> Bob on that van was there a speedo cable?.
> If with a speedo cable then was there an inline magnetic vss sensor?.
> Now ya got me curious.
> Geesh, this is maybe related to what the cruise?.
> Bruce
>
> >
> > The optical buffers I've seen are lime-green in color. They have
> > a three wire cable to the optical head. The edge card conn has
> > two sets of outputs, one for the ecm, the other for cruise.
> >
> > Recently I grabbed a '747 out of a van that had a small black
> > box attached to the ecm mount. At first I thought it was a drac.
> > However, no jumpers and not too much inside. Now I'm thinking
> > it was maybe a magnetic buffer. Next time I run into one at the
> > yard, I'll check more closely for the pickup. An inline mag unit
> > that goes to this buffer would be handy.
> >
> > And yes, I've kinda' wondered about that magnet generator
> > shown on the prints.
> >
> > BobR.
> >
> > Bob Valentine wrote:
> >
> > > No ABS on the van, front or rear.   If it makes a difference this was a
> > > factory TH400 van.
> > >
> > > I'm going to open up the VSS buffer tomorrow and see if there's
> something
> > > like a unused set of inputs for a mag sensor.
> > >
> > > -> Bob Valentine
> > > -> bob at tecmark.com
> > >
> > > At 07:19 PM 12/15/2000 -0500, you wrote:
> > > >
> > > >
> > > >Sounds like the G20 had maybe some version of ABS??.
> > > >For those they need a high resolution VSS, so yes there would be a DRAC
> of
> > > >some fashion.   This is all off the top, of my head seen I've never
> actually
> > > >seen what you have there.
> > > >bruce
> > > >
> > > >
> > > >
> > > >> On a '88 G20 van I just ripped apart the VSS is optical and goes to
> the
> > > >VSS
> > > >> buffer, which is what I expected.  Saved cluster and buffer just in
> case
> > > >> needed.
> > > >> From the '747 diagrams posted on /incoming (specifcally 747ecm5.jpg)
> it
> > > >> shows a "permanant magnet generator"  hooked to the VSS buffer and
> then to
> > > >> the ECM.   I thought '747 trucks used optical VSS?
> > > >> Is there a different VSS Buffer for magnetic and optical?  Is there
> such a
> > > >> thing as a '747 truck w/ a mag. VSS?
> > > >> I looked in the archives and there's a ton of info about the later
> DRAC's,
> > > >> and about eliminating the pass. car VSS buffers for TBI -> '730
> convert.
> > > >> I'm putting a '747 TBI on a '84 GMC pickup.     Might be able to put
> the
> > > >> 88' G20 van speedo guts in the '84 GMC pickup cluster if I need to,
> last
> > > >> resort.
> > > >> -> Bob Valentine
> > > >> -> bob at tecmark.com
> > > >

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