Wiring education needed

[the_buster]

Hi,

I am planning a parallel install of my MS3 and I would like to know if I can "borrow" the grounds from my stock ECU / Wiring. I am able to map out the wiring diagrams to find exact sensor grounds but most of them end up on one wire anyway, is this normal practice? I am a little nervous and want to take my time and thought that a parallel install would be a good approach for my first project.

Thanks,

[jsmcortina]

I would suggest that you run the Megasquirt power grounds directly to the engine. Do not re-use old wires. For sensor grounds, as you are on a parallel install, you don't have much choice there. You may well get dirty readings until the sensors are grounded at Megasquirt alone though.

See: http://www.msextra.com/doc/general/grounding.html

James

[the_buster]

I would suggest that you run the Megasquirt power grounds directly to the engine. Do not re-use old wires. For sensor grounds, as you are on a parallel install, you don't have much choice there. You may well get dirty readings until the sensors are grounded at Megasquirt alone though.

See: http://www.msextra.com/doc/general/grounding.html

James

Thanks,

This was my concern, dirty readings. What if I ran new ground wires as near to the sensors as I can get? the sensor then would have two grounds one for the stock ECU and one for my Megasquirt. Would that be better for Megasquirt sensor grounds?

Thanks,

[elutionsdesign]

No, reread that link.

[the_buster]

No, reread that link.

So the stock ecu would be drawing a signal changing it and be giving the Megasquirt a false/unreliable signal?

I have decided to change my install and use the stock harness and plug the Megasquirt directly to it. This would be far better than my planned parallel install. But now I have to consider the stuff that the stock ecu controlled. At least this way I can get it right and then rewire the engine later for a complete installation with new a new harness.

Thanks.