Hi to all, I'm new on forum and I need your help.

I have Cforce 400 which will not crank. If I turn the key, dash board and lights will switch on. Fuses and relays seems ok, also I have checked for bad connections but I didn't find any problems there. Fuel pump relay is energized, problem is if I measure AUX starter relay in a moment pressing start I can measure 9V instead 12V. So ground from ECU is missing. Can you tell me what are the conditions for ECU to start (neutral indication on dash board is properly triggered)? Also I have tried to connect with universal bluetooth OBD2 to check if I can read some errors from ECU but connection is not possible. I can connect to OBD but connection to ECU is not working.

ECU unit is Bosch MSE 6.0.

Did you accidently bump the kill switch?

Kill switch on left handlebar is not triggered, I have try to measure and switch is working ok. Do you have maybe a wiring diagram?

Also can you tell what are conditions for start? Kill switch, neutral, rear brake?

The kill switch is basically an override that shuts off the starter relay and EFI system. If the fuel pump primes, then it's likely not the kill switch.

Generally speaking, there are several safety locks that can prevent the starter circuit from energizing depending on what position the gear lever is in.

If any one of those safeties fail, it wont start. In general, if it is in park, it should turn over.

A skilled electrical troubler shooter might be able to seek out the problem without a wiring diagram (fuses, relays, weak or high resistance connections, harness plug disconnected, broken wire, etc) but it's a hands on exercise.
It's impossible to make an educated guess from a distance based on current available information.

The problem here is that there is little in the way of useful information to pursue a course of action. A wiring diagram would be key to seeking out the failure.

Lacking that, I would suggest bringing it to the dealer.