And this is from 4.1 ECU pinoutUsually the biggest source of electrical noise isn’t RFI or other radio noise - it’s poor grounding or
having noise injected into the power wires by another device. The MS3-Pro needs to be grounded to
the engine block or cylinder head if at all possible; the battery negative terminal is often an acceptable
second choice. We do not recommend grounding the MS3-Pro to the chassis or sheet metal. You
may either crimp all ground wires to a single lug, or crimp the ground wires on the gray connector to
one lug and the single ground on the white one to a separate lug. The sensors need to be grounded
to the sensor return wire, which grounds them to the MS3-Pro. Grounding sensors to the engine or
body will create jitter from ground offsets
And then there is this from 4.12 of the manual* Both logic ground and power grounds must be connected to the engine block or cylinder head.
Do not leave the logic ground disconnected, as this may result in noise issues or improper operation
Here is a link to The Dub shops wiring diagram. it has made it very strait forward for the most part4.12 Grounding notes
The MS3-Pro uses multiple ground planes to reduce noise. It is important that you connect both the
logic ground at pin 16 on the white connector and all the power grounds on the gray connector to
the battery negative terminal. It is less than ideal, but still acceptable in most cases, to ground the
MS3-Pro to the engine block or cylinder head. Avoid grounding the MS3-Pro to the frame rails or
sheet metal; these points often have issues with rust and spot welds limiting how much current can
flow through them.
Leaving the logic ground disconnected can result in improper operation.
The MS3-Pro has a sensor ground pin on pin 18 of the white connector. All sensors except VR
sensors should be grounded to this pin. Do not ground the sensors to the chassis, engine block, or
other external point, as this can create noise issues.
http://media.wix.com/ugd/9afa64_f5f451a ... 77459e.pdf
Ok now bear with me here this is how i am seeing this
Looks like I should gather all grounds from the grey ampseal harness pins 8,9,7,5,3 hook them to a bus bar-Then take C,L,P,G of grey side 22 pin weather seal connector and hook to same bus bar.
For the white ampseal connector take sensor return pin 18 and logic ground pin 16 and hook to same bus bar as well as sensor logic ground pins F,V,I,M,S from the other 22 pin weatherseal along with the MAP and BARO logic grounds.
All this going to the head or block through the e and N pinsof grey side22 pin weatherseal where the coils are to be grounded
Does that seem right ?
Terry