Zimsmith

try cleaning your self for take to true camera store check it out. they will try to fix and tell you what real issue is. 

I did take it to camera specialist shop and they could not find anything wrong with it then a few months later is happened again. It is very very clean and has been professionally cleaned. It is not that. It is something to do with the 2 x teleconverter being fitted. 

Do you use the grip and large battery? I have found that the higher voltage solved the same intermittent DC/DC fault with TC on my AF-S 80-200 on both D700 and D800E. It might be that an undervoltage caused by the extra resistance in the TC triggers some fault in the DC/DC circuitry.

Hi Merco, 

I don't have a battery pack no. Hmm food for thought though thank you. At the moment it's all working again but it seems to go wrong at the worst possible moment. I've used the lens and teleconverter together for 2 years and only this year the issue started. Never had an issue with the set-up on my D810 or my D4 that I used previously. Maybe I'll look into getting a battery grip. Or just scrap the 2 x teleconverter..