Oliver's ALDC converter...was Re: Hello...short introduction...

[Curt Martin]

> > I've just started working with a ALDC to RS-232 converter made by
Oliver
> > Scholz (from the Fiero e-mail list) to start figuring out the serial
> output
> > of the GM computer. 
> 
> Curt could you give some more information about this converter? I'm
> interested in building a similar device myself. I'd appreciate any info I
> can get.
> 
> John Faubion

John, (and also Scott Feaver and Martin Scarr who asked the same question)

Oliver's ALDC to RS232 converter is a simple microcontroller that plugs
into pins A,B, and E of the ALDC port on the GM wiring harness.  It takes
the 160Hz bits and formats them as 8,N,1 ASCII at 4800bps.  Then pumps that
out a 9-pin d-sub for use with PC serial ports.

The converter has several output modes.  One converts the data to readable
form (i.e. the RPM bits are converted to an string like "2800") with commas
seperating each data value.  A second mode grounds pin B and dumps the
error codes out.  The third mode is a "raw" format (no conversion except
framing the bits into the 8,N,1 format so the PC port can see them as
characters.)

Oliver is into Fiero's, so naturaly, the only two motor/ecm combos that it
decodes completely are the VIN "9" 2.8L V6 and the VIN "R" 2.5L L4

I've hooked it up to my VIN "S" '87 Camaro and it does decode most of the
values (rpm, IAC, coolant temp, TCC, integrator, TPS, O2 rich/lean, Loop,
etc.)  Some of the values that don't decode or I question are the MAT, MAF
(not suprised, the Fiero is a MAP system), and AC settings.  The car is 10
years old and has a flaky idle to start with, so I may have a few bad
sensors... I still have to go through the system sensor by sensor.  I'm not
getting an SES light or error codes, so nothing has failed completely.

Oliver's web page is...
http://www.franken.de/users/degobah/luke/scantool.html

hope this helps,