could be the alternator is about to go out
There should be a roll switch right next to your light switch on your dash to dim the lights with.
Check the alternator.
I have a 1983 GMC Sierra it has no dash,tail lights an brake lights are very dim
If you know where to change the odometer/tripmeter display... Instead of pushing that control, turn it counter-/clockwise to dim/brighten the dash lights.
dial right hand side of the steering wheel
because it is using up lots of power :)
You turn the trip odometer button on the dash.
Check to see if the dash lights dim or if the tail lights come on when the light switch is turned on. If these other lights work then check for a headlight relay. Most likely causes are either the switch or the relay.
Check the grounds for the headlights.
have your battery and alternator checked but first check to see if switch for your dash lights are just turned to dim
Most dash lights have a setting knob to turn the dash lights on and off and to dim them, maybe this switch is off.