turning on headlights dims instrument lights 98 caravan

Hi.. Thanks for all the tips on my previous post about installing a new back tail lift gate.
I have some side effects and the main one is not absolutely crucial, but the instrument lights are now dim when I turn on the headlights. If I dial the dimmer dial the instruments brighten when I dial it so far that it turns on the interior lights. I dont really want to drive with the interior lights on, but it beats turning off the headlights. Actually when it comes right down to it, I just drive not knowing my speed for sure. If I squint and look I can figure it out, but at a glance I'm not sure if i'm going 55 or 65.
Thanks if anybody has any ideas i can try. As it is.. its not really too bad, but not as good as if the instrument lights were bright.
thanks again,
paul

also.. when I got out of the car and locked it before the interior lights were on and they would turn off after a few minutes. Now they are dark always. But if I dial them up to go on, they will go on.