Thread of the brake light switch metering valve

[Ralph the german]

Hi folks,

have new brake lines and master installed and must bled the brake. Have to make the tool instead the light switch. Does anyone know the exact thread of the brake light switch. Not be sure if this is an 1/2"-20 UNF. Read there are many guys confused, cause they get no fluid out the rear, cause they have not set the valve in neutral position......

Thanks
Ralph