try this
1. Switch the unit head source OFF
2. Press (and hold) simultaneously the "U2" and "M" buttons at DEQ, while (always simultaneously) switch the head source ON.
3. If your DEQ is not properly installed, this tip doesn't work (YOU HAVE TO CONNECT THE YELLOW CABLE TO THE LIGHTING SWITCH TERMINAL) Then, when you turn on the lights the dimmer is active and the displayprevents becoming too bright.
or search the web noob