'02 (Gen 1) with near 200k miles on it. The dash illumination will not dim out of daytime mode regardless of dimmer wheel position or lights 'on' vs auto mode. Drive Battery tests out at 297v. Car gets average of 43 MPG in combined driving at altitudes of around 4000 feet as home base. Running Regular 87 or better (depending on what available when I need gas. Problem arose with replacement of the 12v battery. NO other work was done. It is BRIGHT in the car at night with the dash lights in DAY mode!
I think the dimmer switch on those early gen ones may be like the old Corollas and all of that Pop that hole assembly out of the dash and take it apart or stick in another one if you have such a thing some vehicles these things will swap out in and the plugs will be the same many are not that way I mean in Toyota. If you can't find a suitable replacement that will plug up crack open the one you have and see if there's a wheel and a bunch of mechanical funny business If so you'll probably see the problem You can also measure with a test meter that it's actually not doing anything so on and so forth. The electronic gurus should be a long shortly with I would imagine similar things.
I asked because if the dimmer failed you would think it would fail at the position you consitently used it at, becoming all dim elsewhere, or possibly off. To have a dimmer fail and default to open, brightest, highest current transfer, seems counter intuitive.
The dimmer wheel has a click stop at one end of its rotation, which switches the dash lights to the night setting. You're saying that this click stop isn't changing the setting. Sounds to me like you have a defective dimmer wheel switch. I haven't tried this on my '02, but it looks like the panel holding the dimmer wheel will pop out of the dash with some careful prying around the edges. I'm guessing that this should be a fairly routine R&R procedure. The challenge may be finding the replacement part. I'm going to do some searching and will post here if I find anything. OK, looks like this is the part: 84119-47010 Genuine Toyota Rheostat, Light Control. Before shelling out big bucks, I'd try some electronic cleaner spritzed into the wheel opening, like generic "tuner cleaner" from the hardware store. The best stuff is called DeoxIT D5; it's a bit pricey, but a lot cheaper than the switch! Another source for the switch, with diagram: https://parts.olathetoyota.com/oem-parts/toyota-instrument-light-rheostat-8411947010
Thank you! I didn't think of the switch breaking in the "click-on" position. We'll look into that this weekend.
Today I noticed in my '02 that when the headlight switch is "off," the dimmer switch is disabled, i.e., rotating the dimmer switch to any position, including the click stop, has no effect on the dash lights. They remain in daytime mode throughout. The dimmer switch only works when the headlights are "on." Whaddaya know, you learn something new every day. It took only 21 years to discover this little quirk!
