M600 ignition coils testing and grounding

[sheezol]

Hello friends ! This is my first post, so sorry for my language skills.

I am seeking information about ignition coils for my 1999 M600 Dark. Got two questions so let me describe the issue here:

1 - how to measure the secondary coil resistance ? Where to measrue it ? I did try the spark plug cable and the negative wire that goes to the CDI (as well as the frame). It gives me 0 Ohms on both horizontal and vertical coil. The Primary Coil is 5,1 Ohm , but I could not manage to measure the secondary. Where to put the measuring probes ?

2 - Maybe related to the first question. I have completely replaced the wiring and installed a product that "makes the wiring great again" for the classic bikes (dont want to say which one). All is good , the bike is running and everything does work like a charm , but when I ride for about 15 mins and go to the higher rpms then the engines randomly stops , the horn goes on until I turn the key off.

So I went to the manufacturer and we have discussed the coils grounding. And here is where my second question is going to ... The manufacturer sais that the coils should be grounded to the frame from that upper screw (which mounts the coil to the bracket) to the bike frame (even sent me a photo but dont know how to share here).

The only wiring part i left original is the ignition wiring, because it could be used and was in good condition. I got my bike for almost 10 years, made thousands of km on it and never have seen a grounding from coils to the frame. But i have found some information over the web that some Ducati M600 can have the coils grounded.

Maybe the secondary coil cannot be measured by me because of that as well ?

Can anybody please help me finding the final anwser for this ?

Thank You in advance