Well, after having checked the I/S switch connector and wires = ok.
The bulkhead connector = ok.
I think I've found the guilty = the turn signal switch.
As I told before, it's a reproduction (probably made in China). And often reported as junk.
I confirm.... IT'S JUNK... :mad:
When T/S doesn't work (and the voltmeter drop to "0"), if I slightly pull on lever toward me, miracle... T/S starts working again (and the needle stays on 13 volts).
Bad contact somewhere into the switch, and this causes a mess in the circuit.
I need an OEM T/S switch.