Headlights work well w/ ignition switch off. High/low/passing all ok.
When I turn the ignition switch on, there's a strange wheezing sound for a second.

When the ignition switch is on, there are no headlights.

What's the wheezing sound?
Why does the power to the switch quit with the key on?

The more I work on modern trucks, the more I like my 1968 f-250.

C

 

Do you have the Auto on switch? Do they come on automatically when it starts to get dark while driving? If you have the auto switch it probably has something to do with the eye sensor on the dash.