Severe voltmeter needle oscillations

Today, I disconnected the voltmeter.
The turn signals and windshield wipers work.
Ok

I decided to go for a little ride and after some meters, no turn signals anymore
I tried the wipers... nothing. :BangHead:
So, I stopped, turned the engine off and re-started it. At idle, the turn signals and wipers are back
And, once again, after some meters, no more turn signals.
This Demon is really devil-haunted. It turns me mad.... :realcrazy:

François