I would replace the headlight switch.
Find the adjustment for display light brightness. When it is turned all the way up it also turns on the cab light, when turned down it turns off your dash display when the headlights are turned on.
Also check tail light fuse and see if you have tail lights when headlights are on. The dash lights are always on in daytime without headlights and when you turn on headlights if tail light fuse is blown, dash lights go with...so you won't be driving around without tail lights and not know
I believe it's normal. Mikenkc has the fix.
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