Odometer redundancy (ECM capture)

[Carmine]

Jim Davies wrote:
> 
> On Mon, 29 Mar 1999, Terry Martin wrote:
> 
> > Can anyone confirm if either GM or Ford uses a scheme to capture the
> > mileage in non-volatile ram. I think the weird dash cluster (ie '95
> > Caprice) may do it, and make it accessible to the PCM, but haven't
> > tackled the project yet. I'm specifically interested in Ford's EEC's and
> > if implemented, which year/models.
> >
> pre-1998 Ford pickups with the electronic odometer store mileage but the
> new ones seem to have returned to an all mechanical odo [havent tacken one
> out, just looked at it]

Does anyone know what type of vehicle speed sensor is in a 84 Pontiac
TransAm? The manual talks about an optical head behind the speedometer
or a magnetic type in the transmission.  Thanks.

Carmine