Mercury Marine diagnostics?

Hello everyone!

My name is Georg, I'm 34 years old and live in Norway.
I've just joined the group.

Does anyone know anything about diagnosing Mercury/Mariner marine
engines? There is a proprietary tester (DDT) that costs about $1000,
and it connects to both their inboards and outboards. The software
cartridge has to match the specific engine. Such a cartridge costs
about $50, so to diagnose more than one type of engine can be pretty
expensive.

I am looking for an cheaper way of diagnosing my outboard (1999
Mercury 225 Optimax), and if need be write the software for it
myself, but as long as I know practically nothing about the
electrical interface, I really don't know where to start.

I have a broken 1999 200 Optimax ECM. It is contactable and runs the
engine on four of six cylinders, so it should be good enough to play
around with. Markings: VA005481 Motorola Mercury Marine p/n 857127
EFIS69801 09-04-1998 200 DFI ECM 99MY 857127 1 PI82670705.

The DDT connects to the ECM with only 2 wires, and none of them are
connected to ground or vcc, so my guess is that it is some kind of a
current-loop interface, but that's only speculation.

The IC that these two wires connect to is an eight-pin National
Semiconductor thing marked 83AY 52T09, but NS claims that they don't
know anything about this chip. Must be a custom made chip or
something.

All tips and hints will be greatly appreciated.

Regards,
Georg

 
Received on Sun Nov 16 09:02:48 2003