Actually, nope and nope. That is not what's going on. The auto headlights do not turn on when I pass momentarily under an overpass at freeway speeds (2 seconds in darker surroundings). The "headlight on" indicator (green sun) does not light up nor does the electric relay "click" on. The auto headlights are programmed to come on when the ambient light level drops below a certain threshold for 20 or 30 seconds.

Is there a separate light sensor and circuit for the auto-dim instrument light feature? Or is the center dash sensor the same for instrument dimming and headlight activation? I now think it's a bum sensor. Thanks.

 

"Position 3 (“AUTO”)—Headlights and all of
the lights in the position 1
They automatically turn on or off depending
on the darkness of the surroundings.

If you feel that the automatic light control
comes into operation too early or too late,
have the sensor adjusted by your Toyota
dealer."

According to the manual it is possible that the time is set to less than 30 seconds. I have had several vehicles, including my TCH, where the lights will kick on going under an overpass when it it not a bright day out.

 

Okay... How's this for a brain spinner... I turned my headlights to full "ON" at around sunset and drove under a few overpasses on the freeway. The darn instrument lights dimmed again but only for a second! Quick dim... then bright again... Quick dim... then bright again. Go figure? I can manually override the dimming by turning the rheostat dial all the way to full bright (click).

Without looking like an idiot at the dealership again, what should I suggest they look at? And, this time they better not disable the DRLS! Is there a separate light cluster sensor for ambient levels? The manual is of no use here. Someone have a tech manual?

 

There are three levels associated with the dash lights. One is during the day, the next is at dusk, and the last is at night. The first two, as far as I can tell, do not involved turning on the headlights. The different is probably turning on the running lights. I don't know if there is a way to change that, but, take a look at the customizable features.

 

Nope. They've adjusted it twice. Looks like Toyota over-engineered this simple device.... arggggg... I'll just stick to manual override on the dimmer until it's fully dark outside. That still works fine. Thanks for the info.

 

I actually just leave mine at the lowest setting because the radio and HVAC lighting is far too bright for me at night. I never play with it. I would keep the gauge lights brighter if there was a way to dimmer the radio/HVAC lights separately. I am still thinking of installing a second rheostat or resistor on the line to the radio/HVAC after the rheostat.