Dimmed Backlit Dash and Radio/HVAC Lights

[EddieC]

I just replaced the Head/Fog Lamp switch (with oem) and all the functions work but the intermittent dim problem persists.
Is there a light sensor somewhere? I see a little dark half sphere far forward on the dash that may be it, but I hope not because it must be inaccessible from below.

 

[mikez71]

I removed my front panel to pop the sensor out..
definately not accessible from below or through the radio hole..

 

[EddieC]

I removed my front panel to pop the sensor out..
definately not accessible from below or through the radio hole..

Not my year but I watched a video on a 2006 and it was major surgery to get the dash top panel off.
Not possibly worth it just to chase dimmed dash reporting lights.

 

[mikez71]

It's not too bad, but you risk breaking some clips forsure..

Every morning lately the dash is dim. Bright enough for sunglasses (cloudy) but my dash is dark.
I will be happy to finally wire a switch, I'm just looking for a good 3 position dial ...

 

[EddieC]

It's not too bad, but you risk breaking some clips forsure..

Every morning lately the dash is dim. Bright enough for sunglasses (cloudy) but my dash is dark.
I will be happy to finally wire a switch, I'm just looking for a good 3 position dial ...

My Tahoe has a dial to adjust the gage and radio lights and I leave it fully bright (just below illuminate dome) but when the system dims it's not bright enough.

Now for a "DUH" moment. I ran across a video showing where a fellow cleaned the little ambient light sensor nipple and it affected his DRL to headlight function. Worth a shot.

 

[EddieC]

I removed my front panel to pop the sensor out..
definately not accessible from below or through the radio hole..

How does that get done?
I suspect mine because the headlight switch is set to automatic but the lights are on in the day.

 

[mikez71]

If I remember right, you remove the a pillar trims.
1 screw up top (phillips or 7mm?), grab handle bolts on passenger side (10mm? after prying the covers off)
Then there are 5 or 6 clips along the edge facing you, so you just have to pry it up..
OF COURSE you risk breaking the tabs on the defroster panel that hold the clips, and the little plastic receptacle holes underneath.

I'm planning to add a parallel resistor to ground to reduce the sensitivity to darkness. (as well as a switch to manually select dim/auto/bright)
Lately it's been dim every morning despite being plenty bright outside.

I bought an adjustable resistor to help me pinpoint the resistance value that I need.
Will post details if I ever get to it.. You bringing this up has got me thinking about getting on it!

 

[mikez71]

7 clips hold the defroster panel on. 3 on each end ~6" apart. 1 in the middle.

The backlighting changes modes on key in:
from dim to day once resistance drops below 3.14k ohm
from day to dim once resistance rises above 4.92k ohm

The values were measured by manually twisting a variable resistor before repeated keyon/keyoff cycles.
Then once the adjustment caused a change in backlight on keyon or keyoff, I would remove the resistor and measure it.
The closest I could get after testing a few cycles, didn't feel the need to set the resistance to a precise value and keep testing..

So between 3k and 5k, it appears to default to the previous shutdown mode.
(Only tested with repeating key-on/key-off cycles, not shutting down for any length of time)

With the engine running, if the resistance is hovering around 3k or 5k, it can take several seconds to change. (upto ~20seconds?)
But if the resistance is low or high enough, it will still take ~3 seconds to change mode.