Don't mess with the dimmer switch, mess with the clock itself. If you pull it out, you will see a ground, constant 12+, accessory 12+, and a dimmer line (I don't know which colors are which, so if you can get a volt meter to do some testing you'll figure it out). You can just cut the dimmer line and your clock will be full illumination all the time...... just remember when you turn your lights on and it is dark outside the clock will look a whole lot brighter than the rest of your dash.