I've got a dimmer problem with my dash lights on a '04 . Dash lights are dim, but radio, and heater light are fine. Dash light will be real dark, heater and radio bright, and when I dim the lights, heater and radio will dim, but dash lights will actually get a little brighter. Not enough, just weird they come up when turning the others down. I replaced the dimmer switch, but with junkyard stuff. Did they have a problem with the dimmer switches? I suppose I should try a new switch? Ground?

 

Your dimmer switch is not the problem. From the schematic below you can see the instrument cluster, radio and heater illumination circuits are all in parallel. If the dimmer works for any one of them it works for all of them. Your problem is much more likely to be in the instrument panel lighting or the wiring going to the instrument panel.


Since the radio illumination is working normally it is not likely part of the problem but it is important for troubleshooting purposes to understand that the radio illumination works differently than the all the other illumination circuits.



The reason for this is that the radio display (which in my case includes the digital clock) must be brighter in the daylight and dimmer at night. This day/night switching is controlled automatically by the ambient light sensor in the dash or manually with the headlight switch.

 

Thank you, I appreciate that information. I will track it down.

 

If you need instructions for removing the instrument cluster, see the recent post entitled: