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Does your truck always think it's night time? How to fix ambient light sensor issues.

31K views 64 replies 34 participants last post by  pomarco  
#1 · (Edited)
Hi everyone,

As some of you know, I've been infuriated about how my truck always thinks it's night time. It would turn on the lights and dim the dash unless the sun was shining directly on the sensor. It could be broad daylight, not a cloud in the sky, so bright I'm wearing sunglasses...but if the sensor was in the shadow of the A pillar, roof, trees, anything...dark dash and lights on.

What. The. Heck.

A massive thank you to @hoitzed who pointed me down the right rabbit hole. It was very old, went to different forums, and had tons of conflicting information, so I thought I'd bring it to top of mind so everyone can fix it themselves. It is really easy, and hard to mess up. No special tools required. If you can swap your headlights to LED, you can do this. If you can swap your map and dome lights to LED...you'll be a pro! Disclosure - do this at your own risk. It's not covered under warranty if you mess something up, and don't blame me if you do...yes it's easy, but you're dealing with sensitive electronics, and if you're not comfortable with the risk, don't do it.

Step 1 - remove the sensor housing

The sensor housing is the little eyeball thingy in the very middle of your dash. It's held in place by a trapezoidal piece of trim, shown below (note that the sensor housing itself is not shown in this picture!). If you pry up on the front (facing the window, not you) part of the trim, it will pop up. Use something plastic to avoid scratching it. Once you've popped it out, you can remove the trim piece from the sensor housing by rotating it and then pulling it off...it's easy to see how to do this when it's exposed. Last but not least, unplug the sensor housing. You have to push quite firmly on the two side tabs to unlock it...just be patient and be firm yet gentle, and the plug will come off. I had to pull my sensor somewhat firmly and gently to get it out enough to reach the plug, it you can do it without trouble...gentle firmness and patience are the keys to step 1!

Image


Step 2 - Remove the sensor from the housing.
You'll want a small flathead or pick or something to depress small tabs in this step. The "bottom" of the sensor housing is one piece, that runs from the connector, to the rounded part. There are four tabs in total to press in to detach it. The first two are right at the edge of the connector (red circle), and you should do these first. The other two are midway up the rounded part and are a bit more difficult...depress one side, wiggle things so it can't reengage, then do the other side. Again, firm yet gentle. When you've separated the two housing halves, you can literally just pull the sensor out. It's a tight fight...I know I sound like a broken record, but be firm yet gentle!

Image


Step 3 - Marvel at how, for 6+ years, GM has been purposefully messing up the sensor, and continues to willfully ruin an otherwise well designed device.
Seriously...THEY COVER IT IN AN OPAQUE WHITE GOOP. Like, the sensor that's supposed to detect light? They block it from the light. WHAT?!
We're going to fix that by removing the goop. It is gross, and sticky, and nearly impossible to cut, so this is where it's a bit more of an art than a science. Take a deep breathe, crack a beer, and get to work...but before you do, read step 4 to see what the circles are all about.

Image


Step 4 - be thoughtful about what you want to do.
It turns out this sensor is actually a number of different sensors all on the one chip. My research tells me it does three things - blinks red when the alarm is active, measures the "solar load" to help the AC keep you cool, and measure the ambient light to dim the dash when it's dark out. We only want to affect the last one of these three things. Many, many other people just peeled all the goop off without issue...the AC might be a bit trigger happy but most people reported no issues, and the LED for your alarm might be a titch brighter, but who cares. I'm personally a bit of a stickler for perfection, and I did care, so I only wanted to remove the goop from the ambient light sensor. However, I wanted to clear as much of a path around them as possible, so light from any angle would trigger them.

In the photo above, the upper left side of the board is the "back" - the part that faces into the cabin when installed. Just remember that the connector pins always point to the right. The LED for the alarm is at the back, facing the cabin, where the red circle is. There are two solar load sensors - one on each side - in the middle, under the yellow circle. The ambient light sensors are at the front, under the blue circle, and there is again one on each side. We just want to uncover the front parts. Now, as I mentioned, this stuff is so goopy and sticky it's nearly impossible to cut. It's much easier to use a pair of tweezers, or even your finger nails, to pry little chunks off. Be very very careful that you DO NOT touch or scratch the circuit board or sensor with anything metal at all. Seriously, I know it's gross, but just use your fingers. I was able to slowly but surely pry away the front sensors entirely, as well as a nice "dome" around them. The solar load sensors are still mostly covered, and the LED is still completely covered. The two pics below show what I mean. You can do this too, or as noted above, you can just pull all the goop off (much easier, but may affect your AC).

Image
Image


Step 5 - put everything back together.
No pictures here, it's very easy. Just literally reverse the previous steps...Slide the sensor back into the top of the housing. Clip the bottom half of the housing back in place. Plug everything back in. Slide and clock the trim piece that holds the housing on, and snap it back into place - insert the back part (facing the cabin) first, and then snap the front part back in...the exact opposite of how you took everything apart.

Step 6 - marvel at how the technology actually does what it should
Oh my gosh, it works. IT FREAKING WORKS. If it's dawn or dusk or really quite dark out, or of course night time, the truck turns on the light and dims the gauges and display. Just like it should. If it's sunny out or even a brighter cloudy day, it turns the lights off and brings the gauges /display to full daytime mode. It's gone from being 10% accurate to 95% - there's only been maybe one time where it was relatively dark in the morning, but still "daytime", that it took longer than I'd hoped to brighten things...but it's still a quite literal night and day improvement from before.

Good luck!
 
#2 ·
Not a problem here on my 16.
 
#3 ·
It tends to do this time of year more since the Clocks went back an hour.
Yes, if it experiences shade for a period of time.... It thinks it is dark out.
Usual about 9 months of the year not really an issue
 
owns 2017 Chevrolet Colorado Z71
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#7 ·
My 22 does it so much I’ve just turned off the automatic headlight feature. Like old school I need to remember to turn the head lights on when it gets dark.
 
#8 ·
Hi everyone,

As some of you know, I've been infuriated about how my truck always thinks it's night time. It would turn on the lights and dim the dash unless the sun was shining directly on the sensor. It could be broad daylight, not a cloud in the sky, so bright I'm wearing sunglasses...but if the sensor was in the shadow of the A pillar, roof, trees, anything...dark dash and lights on.

What. The. Heck.

A massive thank you to @hoitzed who pointed me down the right rabbit hole. It was very old, went to different forums, and had tons of conflicting information, so I thought I'd bring it to top of mind so everyone can fix it themselves. It is really easy, and hard to mess up. No special tools required. If you can swap your headlights to LED, you can do this. If you can swap your map and dome lights to LED...you'll be a pro! Disclosure - do this at your own risk. It's not covered under warranty if you mess something up, and don't blame me if you do...yes it's easy, but you're dealing with sensitive electronics, and if you're not comfortable with the risk, don't do it.

Step 1 - remove the sensor housing

The sensor housing is the little eyeball thingy in the very middle of your dash. It's held in place by a trapezoidal piece of trim, shown below (note that the sensor housing itself is not shown in this picture!). If you pry up on the front (facing the window, not you) part of the trim, it will pop up. Use something plastic to avoid scratching it. Once you've popped it out, you can remove the trim piece from the sensor housing by rotating it and then pulling it off...it's easy to see how to do this when it's exposed. Last but not least, unplug the sensor housing. You have to push quite firmly on the two side tabs to unlock it...just be patient and be firm yet gentle, and the plug will come off. I had to pull my sensor somewhat firmly and gently to get it out enough to reach the plug, it you can do it without trouble...gentle firmness and patience are the keys to step 1!

View attachment 440724

Step 2 - Remove the sensor from the housing.
You'll want a small flathead or pick or something to depress small tabs in this step. The "bottom" of the sensor housing is one piece, that runs from the connector, to the rounded part. There are four tabs in total to press in to detach it. The first two are right at the edge of the connector (red circle), and you should do these first. The other two are midway up the rounded part and are a bit more difficult...depress one side, wiggle things so it can't reengage, then do the other side. Again, firm yet gentle. When you've separated the two housing halves, you can literally just pull the sensor out. It's a tight fight...I know I sound like a broken record, but be firm yet gentle!

View attachment 440728

Step 3 - Marvel at how, for 6+ years, GM has been purposefully messing up the sensor, and continues to willfully ruin an otherwise well designed device.
Seriously...THEY COVER IT IN AN OPAQUE WHITE GOOP. Like, the sensor that's supposed to detect light? They block it from the light. WHAT?!
We're going to fix that by removing the goop. It is gross, and sticky, and nearly impossible to cut, so this is where it's a bit more of an art than a science. Take a deep breathe, crack a beer, and get to work...but before you do, read step 4 to see what the circles are all about.

View attachment 440732

Step 4 - be thoughtful about what you want to do.
It turns out this sensor is actually a number of different sensors all on the one chip. My research tells me it does three things - blinks red when the alarm is active, measures the "solar load" to help the AC keep you cool, and measure the ambient light to dim the dash when it's dark out. We only want to affect the last one of these three things. Many, many other people just peeled all the goop off without issue...the AC might be a bit trigger happy but most people reported no issues, and the LED for your alarm might be a titch brighter, but who cares. I'm personally a bit of a stickler for perfection, and I did care, so I only wanted to remove the goop from the ambient light sensor. However, I wanted to clear as much of a path around them as possible, so light from any angle would trigger them.

In the photo above, the upper left side of the board is the "back" - the part that faces into the cabin when installed. Just remember that the connector pins always point to the right. The LED for the alarm is at the back, facing the cabin, where the red circle is. There are two solar load sensors - one on each side - in the middle, under the yellow circle. The ambient light sensors are at the front, under the yellow circle, and there is again one on each side. We just want to uncover the front parts. Now, as I mentioned, this stuff is so goopy and sticky it's nearly impossible to cut. It's much easier to use a pair of tweezers, or even your finger nails, to pry little chunks off. Be very very careful that you DO NOT touch or scratch the circuit board or sensor with anything metal at all. Seriously, I know it's gross, but just use your fingers. I was able to slowly but surely pry away the front sensors entirely, as well as a nice "dome" around them. The solar load sensors are still mostly covered, and the LED is still completely covered. The two pics below show what I mean. You can do this too, or as noted above, you can just pull all the goop off (much easier, but may affect your AC).

View attachment 440725 View attachment 440727

Step 5 - put everything back together.
No pictures here, it's very easy. Just literally reverse the previous steps...Slide the sensor back into the top of the housing. Clip the bottom half of the housing back in place. Plug everything back in. Slide and clock the trim piece that holds the housing on, and snap it back into place - insert the back part (facing the cabin) first, and then snap the front part back in...the exact opposite of how you took everything apart.

Step 6 - marvel at how the technology actually does what it should
Oh my gosh, it works. IT FREAKING WORKS. If it's dawn or dusk or really quite dark out, or of course night time, the truck turns on the light and dims the gauges and display. Just like it should. If it's sunny out or even a brighter cloudy day, it turns the lights off and brings the gauges /display to full daytime mode. It's gone from being 10% accurate to 95% - there's only been maybe one time where it was relatively dark in the morning, but still "daytime", that it took longer than I'd hoped to brighten things...but it's still a quite literal night and day improvement from before.

Good luck!
Nice writeup ! Thanks. Moved it to the "How-To" section.

FWIW I believe that is white RTV, super common in electronics and also used in various other forms to make press-fit automobile gaskets.
 
#12 ·
My annoyance isn't that it triggers night mode in a brief shade, but it stays triggered way too long after the full light is hitting it again. This tells me its probably a programming thing.
I just taught myself to turn the day running lights off to restore the full display light.
 
#13 ·
I thought so too but mine would stay off forever. It works much better after this change. I think the programming is sound, the gain on the sensor just isn't enough to trip the hysteresis back to the right value. Like it's always riding right on the edge of dark mode, instead of riding in the middle where it should.


It was in the 2 Gen Section...
But with your Editing
It changed the Thread..
And made an Excellent How To...
So ARC just was letting you know that and that as a Moderator we can move the Threads to correct location..
hehe yeah, I accidently clicked "publish" before I'd even started...between the wrong subforum and the early publish I swear I wasn't drinking :ROFLMAO: Thanks for getting it in the right spot!
 
#15 ·
Nice writeup. I too was tired of the annoying, premature switch to night mode, so I gave this a shot, only I removed all of the “goop.” No issues at all. Haven’t driven the truck enough yet to fully gauge the improved accuracy, but I’m hoping your experience applies.

Note: When night mode inevitably switches on at dusk (and earlier), I typically turn the lights off to the left, then press the fog lights. I’m running the Gen5 harness, so this illuminates just the headlight LEDs and fog lights, which looks killer.

Image
 
#17 ·
Love this! I'll be absolutely doing when time permits. Some people don't know what we are talking about with this issue but man I hate the stupid light sensor sensitivity. Had been meaning to figure this out myself, much thanks!
 
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#18 ·
I can verify this works.

I tested it by covering the sensor with a folded up newspaper on a bright, sunny drive home, headlight switch on auto. Within 20 secs, the dash info center and the infotainment screen dimmed. I removed the newspaper and again, within 20 secs, it went back to full brightness. Before, it took a very, very long time to return to full brightness. Before, on a bright, sunny, cloudless day, if I was sitting at a stoplight and the sensor was blocked by the shadow of the A-piller, it would trigger the dash to dim. Today, after the mod, I tried to shade it to trigger it and it wouldn't dim. So, I'd say it's a success.

I modified mine the same as the OP, Dennon, and removed the gooey, sticky substance from the light sensor to the front of the truck.

Thanks for the research and write-up, Dennon! Well-done!
 
#23 ·
I just did this. Took me about 5-10 minute. Great write-up @Dennon !!


I used a 90 degree trim removal tool but any plastic trim removal tool should work. If you're careful, you could use a small screwdriver (flat blade), just don't scratch your dash. Just pry up from the window-side of the plate and it will pop out.
 
#26 ·
I like this, so I decided I will order a replacement sensor and modify that one and install it. That way if I don't like it I can reinstall the original. It is only like 28.00 plus if I would ruin it, I still have the original still in place. Nice write up, by the way.
 
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#28 ·
i did this the other day, works good. had all my windows tinted last July when i bought the ZR2. not dark tint and the windshield was tinted for UV and heat rejection here in Vegas. Head lights were always changing from day to night during the day. this fixed it , thanks for the writeup.
 
#31 ·
I'm going to do this mod. Just ordered a replacement on Amazon(less than $10.00!) to modify and install.
 
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#33 ·
Thank you Dennon for this write-up, I did this mod and can confirm it works as perfectly as stated. Stays in daytime mode even when overcast or shade, and switches to night when its actually needed. Instructions are very good and pretty much anyone can do it. Lighting now functions as I want it to.
Thank-you
 
#35 · (Edited)
Thank you @Dennon. Another frustration eliminated.

I removed the entire blob of sticky compound from mine. It should work the same either way. The sensors are a pair of photodiodes mounted back to back on the forward upper corner of the board and appear to be wired in parallel. Removing the forward half of the compound exposes those.

The alarm blinker LED is on the upper rear of the board. Uncovering that at the same time should have no effect, maybe a slight increase in sensitivity to in cab lighting.

I don't expect any issues but will add to this post if I have any. The translucent compound was likely intended to serve a diffusing function making the sensor omnidirectional. The structure has enough supporting features that a potting compound isn't needed and most of those are opaque anyway. For the time being the sensor has higher gain and is more directional. I have photo diodes in the hobby bin and I'll tack one on looking upward if needed. Too soon to tell now.

I laid the board down on a microfiber and brushed outward with a toothbrush to remove the small amount of compound that didn't pull off. There was still a bit of S&W schmutz in this pic but it shows what is under that blob.

Image


Oh - Thanks again!
---------------------------------------------
If anyone is interested in what is in that sensor - this should be close if not correct. One drawing in the upfitter manual depicts one of the signals to be a square wave or maybe some type of PWM. It is not, all these signals are analog and pulled up to a reference through a resistor at the source.
Twilight in conjunction with a sensor in the mirror help control LCD mirror dimming.
Ambient provides data for automatic headlights and dash dimming.
Also on board are a cab temp sensing thermistor and the alarm flasher.

Image
 
#36 · (Edited)
Well, My bad, I just went out and checked once again and it does pop up out of there, I just had to find a small enough tool to get it loose. I have a replacement coming in the next day or so then I will get this done. Great write up and pics for illustrations.
 
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#37 ·
Well, I got the new sensor through Amazon for like 10.00 and I took the goop stuff off just over the light sensor and it only took me about 20 minutes to complete removal and reinstall. I took the original sensor and removed all the goop stuff from the sensor. I'll see how the first one works, or I can switch it out with the other.
 
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#38 · (Edited)
I finally got around to doing this & managed to get the goop just off of the 1 sensor on the right side, as the OP suggested, leaving the rest of the white goop on there, covering the other 2 sensors.

Put it all back together and started her up.

It was daytime & the dash/instrument/gauge lights came right on, at full brightness as they should have.

My really noticeable issues, were more in the morning as the sun was rising - my dash/instrument/gauge lights seemed to stay very dim, for far too long, in my opinion.

So, I'll have a better idea how well it works tomorrow as daylight breaks, while I'm driving in the early morning.

But, the initial indications are good.

Thanks to @Dennon for the detailed write up & pics.
 
#39 · (Edited)
Looking forward to your update @Gray Fox 19 .


Me? I followed this thread a while back because my '20 Z71 also thinks it's night time way too late in the morning, and way too soon in the late afternoon. Turns to night mode while it is most definitely still sunny and bright out... which is the issue addressed here.
Now, I'll be honest that, for now anyway, I've not done any mod to correct the issue. I've just been living with it, but hating it every time I can't see my screen because of it.

Here's my contribution to the thread, although I don't suspect it will help with any other solution as you'll see.
My sensor worked just fine when I got my truck.
It continued to work just fine until a certain trip to the dealership for some warranty work, specifically a radio software update.
Maybe you have read about, or are aware of the issue many have had with "ghosts in the machine" of their infotainment center; rebooting to flash screen on its own randomly, dead controls, changing volume on its own, etc.? There is a TSB (22-NA-033) about it. See this thread for reference: https://www.coloradofans.com/thread...do-lt-crashing-rebooting-with-apple-carplay.420141/page-9#nested_reply_top_post (there are several threads about the issue, but this one includes the most info IMHO.).
Anyway, as the TSB reads, a "radio software update" is the prescribed fix, and I had this update performed by a dealer at the end of May 2023.
Thankfully, the update did cure the problems I was having with the infotainment system. (knock on wood)
However, I'm sure most of you know, the "radio" is part of the brain of our trucks, and includes much more than the radio, apparently including things like this light sensor.
My sensor, or as I suspect, the programming for this sensor, has been fagazy since this update.
No, I did not go back to the dealer about it. The problems with the radio were a much bigger issue for me, and I'm just glad that is fixed. To be clear it wasn't just the radio, but every aspect of the infotainment system that was fubar; radio, all apps, climate control, navigation, bluetooth connections, etc.
They all work now.

I won't take the chance that going back to the dealer to reflash again might solve the light sensor issue, but mess up the infotainment center again. I'll leave well enough alone for now. Yeah, I'm not a dealership service department fan. In general.

Alas, I babble. My point is that I believe the sensitivity of the light sensor is programmable in some way. I don't think the core problem is the mechanics or electronics of the sensor itself, I think there is programming flashed in that sets the range, and that's what I think is wrong. If there was a procedure to adjust that, that I could have confidence in, I'd try that, but AFAIK there is not, it's all built into the one flash version (i.e. V807, V809, V810). So, I'm not going to F with the software for now.
I may do the mechanical mods shown in this thread if it annoys me enough, so thank to all for posting about it.

I'm posting the story in case there are software wizards out there that can either come up with a solution, or help Chevy fix their stuff (OK, I know that's unrealistic, lol).
I've worked on some Fords and have used FORScan. If you don't know, FORScan is an app-like thing that allows users to control a lot of details in the vehicles programming using an adapter through the OBD port. It allows adjusting features very specifically, item by item. It is a pretty cool thing, but I do not believe there is anything like it for GM or Chevy. Other than the dealer I suppose. I understand they have much more ability to mod programming than the owner's or private shops do.