I have an 85 truck with 22r every time I turn on headlights alternator stops charging. Checked all the wiring going to lights...no obvious problems just curious has anyone else had this problem? multi switch possibly?

 

You have checked this with a multimeter ??

When you turn on the lights the charge light comes on??

Or you just see the voltage drop under load

Is the belt tight??

Battery, The terminals and cables all in good shape.

How is the wire coming off the B terminal of the alternator.

More like a charging problem then a light issue

 

yes goes from 14.5 volts to nothing, new belt new alternator new battery and terminals... but only when headlights are turned on...