trying to crack mid-80s Chrysler serial code

[Chris Papademetrious]

Hello folks!

I'm a brand-new list member.  I've owned mid 80's Chrysler turbo cars for a
few years.  Anyone fortunate enough (?) to own one of these beasts knows
that they are only happy if fed alot of attention.  Well since my car is
always doing something odd, I thought it would be nice to see the car as
the computer sees it.  I've seen diagnostic tools that plug into the serial
connector, and give real-time readouts on coolant temperature, battery
voltage, engine RPMs, etc.  I'm assuming this diagnostic connector is
simply a serial connector.

What I'd like to do is design some hardware to read this serial stream, and
allow the results to be displayed on an LED or LCD readout.  I'm hoping I
can pull it off nicely enough to integrate it into the center console,
since there's currently an open spot that's perfect for a panel display.

Question is, does anyone have any information that can point me in the
right direction in terms of baud rate, voltage levels (I'm assuming 12V
inverted, from the little bit I've been able to glean from the archives
here), and protocol?  I know where the RTS/CTS pins are on the logic
module, I just need to know what to *do* with them! :)

As always, I will share all information and designs I come up with from this!

Thanks in advance.

 - Chris