Yes there is. You simply twist the tachometer reset nob counterclockwise to dim.
Check dimmer switch.
bad wireing or your insterment panel dimmer switch is bad
The panel dimmer control is to the right of the headlamp control. If you roll the panel dimmer control up past detente (the catch), it is in the full up position and all of the interior lights will remain on. If you roll the panel dimmer control down past detente, the interior lights will turn off (unless they are individually turned on in which case the panel dimmer switch is overridden). I would also suggest the question could be related to interior lights that keep coming on due to a stuck door ajar switch. See "Related Questions" below for more about that.
A rheostat is a variable resistor. Examples are a volume control knob or an instrument panel dimmer switch. As the resistance is increased in the switch the volume will lower or the instrument panel lights will dim.
On many cars, there is a dimmer switch which controls the instrument panel lights. If this switch is turned all the way, it may cause the overhead light to come on. The overhead light will then stay on even after doors have all been closed. Find the dimmer switch, close the doors, wait 30 seconds, and then turn the dimmer switch.
The trip odometer switch on the odometer itself is the dimmer on Toyota Sienna. If you turn this switch all the way to the left your panel would become dark. Simply turn the switch to the right and all panel lights would come on. I had a similar problem and the manual bailed me out.
Dimmer switch (rheostat burned out?) Headlight switch?
It is probably either the switch or a bad ground somewhere. Try the switch first. On my truck the switch itself is going bad. most of the time if you just keep turning the switch on and off then it will come on. If not you'll have to replace the switch. Logic tells us that IF the headlights [high and low beams] are WORKING, then the dedicated HEADLIGHT dimmer switch is OK, as the headlights are the only thing that dimmer switch controls. The HEADLIGHT dimmer switch is ONLY in the headlight circuit, not the other related circuits such as instrument panel and parking lights. On the other hand, there is a SEPERATE DIMMER switch, usually in the MAIN light switch, for controling the brightness of the instrument panel lights, and as answers 1 and 2 suggest, the problem is more likely in the main switch which controls the instrument and parking light circuits, but again, not in the switch dedicated to controlling high and low beam headlights.j3h.
IIRC, yes. Check the cabin fuse panel. Also check the dimmer switch
PULL the light switch out (must be in lowbeam setting for fog lights to work)
Beside your headlight switch in the dash is your gauge panel dimmer switch ( Rotate the switch all the way up to turn on the interior lights )
The dimmer switch if for the instrument panel lights. The high and low beam switch is for the headlights. On most older cars the high and low beam switch was on the floor. Most cars have it on the turn signal lever now.