GBM wrote:
Does anyone have a detailed wiring schematic for a yanmar 2QM15?

I have two simplified schematics but they don't help much.

I am trying to find out where the red wire connected to the "B" stud on the
alternator goes to and what the engine mounted fuse protects. All I know,
is that the red wire ENTERS the wiring harness and that another red wire
EXITS the same harness and connects to the starter and this is the
alternator output to the batteries.

The fuse is mounted on the engine. The schematic in the parts manual shows
that this fuse is on a connection from the "B" terminal to the panel, but
the schematic is suspect because it does not show the connection to the
starter or batteries.

Hope the question is clear

GM

Which alternator does your Yanmar have? Mitsubishi? Nippon Denso?
Hitachi? Valeo?

Yanmar bolted a host of different units onto their engines.
Anyhow B+ goes to red right to the battery cable stud on the starter
"F" or "D+" or "L" goes to the key switch to excite the unit. if the
alt. is equipped with an "L" terminal that means "LIGHT" and should be
recommended to run through a small 12v bulb before attaching tot he key
switch. therefore, when the key is "on" the light glows showing a
drain because the alt. bulls about a 4-5 amp current. Whne you start
the engine, the power will feed back through the light, and equalize
with the battery output and the light will go out, showing charge.