Hi INVudc is 345v. I have checked the resistances on the output pins (6,7) of the 4 Ic's mentioned. All are at 60 ohms & 120 ohms with the socket unplugged from the inverter. They all have 3.3v on pin 2 and earths on pin 3.

It seems like the vcu is inhibited some how.

Is there any way to check the ...

Interesting that 16v limit is ok. I don't have an oscilloscope but savvy can shows activity from the IVTs on can2 but not Can1. I will try your suggestion re pin 5 and get back to you.

So near yet so far!!!