What is the best way to connect my LC1 to the My15M.  My V11 has the socket to connect to one O2 sensor.  I also have an old OEM sensor that I can cut the plug off.  I would like to able to use the original bike harness rather than have two plugs onto the My15M.

It would be helpfull if anyone knows which wire colours from the OEM O2 sensor plug fit to the LC1 and the best way to power the LC1.

I mounted the LC1 with tie wraps under the MyECU, and used the diagnostic plug wiring in my harness to bring in the signal, since the diagnostic plug is no longer used.  If you check my link, you will see a red and a blue wire going from the harness connector to the O2 input connector.  You can use either one of those pins to make the internal connection since you are using one O2 sensor.  Based on Carl Allison's V11 schematic, it is probably either pin 9 or pin 10 that you can use internally, and pin 1 or 3 of the diagnostic connector.  Here is the link to my pictures, followed by the link to the V11 schematic.  I do not have a V11, so this is all at your own risk, and my advice is free, so you are getting your money's worth. ;)
https://picasaweb.google.com/106090307548421468637/MotoGuzziProject?authkey=Gv1sRgCOvxnMyo6oiyfQ

http://www.thisoldtractor.com/guzzi007/schematics/1999_V11_sport.gif

Hope this helps.

At a guess there are 4 wires
There would be two for the heater - gnd and 12V ( possibly supplied by fuel pump power )
There are two for the sensor - gnd and signal.
Shouldn't be too hard to figure out what's what.

Yes, I ended with a cluster of ground wires at the point where the wiring harness ground wire attaches to the ECU case, and I spliced a weather proof fuse holder into the +12V line from the LC-1 going to the fuel pump relay ( the red wires visible in the picture showing my battery compartment).  As I remember from the LC-1 instructions, the grounding was a critical issue, which was why I did it that way.  I ended up having to get a longer screw for the ground connection, because the original screw was too short after adding the stack of ground lugs.  There are three ground wires: a bare shield wire, the power ground, and the sensor ground.  If you add the calibration circuit, it needs a ground wire also.

Many thanks for the advice.

Unfortunately your first link does not work.

I understand the O2 sensor has four wires, two for the heater and two for the signal. I can identify the heater wires from the Guzzi V11 wiring diagram but do not know which of the two signal wires is ground. The two wires go to pins 2 and 8 of the OEM Ecu.

Carl's diagram is for the bike without 02 sensor (without Cat).  Please refer to the 'With Catalyser' diagram.  I don't understand how you are using the three pin diagnostic socket.  I see diagnostic plug pin 2 is +12v from the Ecu relay, but I believe pins 2,3 are the serial lines for the diagnostic function.

I have tried to paste a section of the wiring diagram to this post without success.

For some reason, part of the link is on the line below.  You would have to paste the two pieces together, or find where I posted the link earlier in this forum, or maybe Cliff can fix my link.  MyECU does not use the diagnostic function, that is for the Marelli unit, I believe.  I'm glad you have the correct schematic to refer to.  In my Sport 1100i, pin 2 is ground, so I used 1 and 3 for my O2 sensor lines.  The diagnostic plug just shorts the lines together in the M16 unit, and there is a diagnostic light that flashes to give a trouble code.  I don't know what they did in the M15 unit for the V11. If you look at the PCB for your MyECU unit, you can see if either of those pins are connected to anything on the PCB.  If the pin is empty, you can use it for connecting.

OK, got the link working.  I see you've been having fun with the old girl.  I love seeing modifications like yours.

However, the two bikes and ecu's are different.

Thanks for the suggestion though.

I see what you mean.  I looked at the V11 Cat version, and I see that the OEM O2 sensor uses pins 8 and 15 on the MyECU, but pin 8 is being used for something else, while pin 15 appears to be empty.  Maybe someone who has a My15M can explain what pin 8 is for.

Pin 8 is the o2 input, you can see the track going to the 3 pin header.
Not sure why you think it is for something else

YaBB Administrator wrote on 07/24/12 at 19:05:28:

Pin 8 is the o2 input, you can see the track going to the 3 pin header. Not sure why you think it is for something else

I got confused looking at the artwork for the My15M because there was no identifier for the three pin header, and I was not sure what T8's function was.  I should have realized that R12 and R12b are the O2 input resistors.  Sorry. :-[