Disable auto-dimming? (ambient light sensor)

[mikez71]

FOR THEM WHO WANTS TO DISABLE THERE DRL - Chevrolet Forum - Chevy Enthusiasts Forums

Tahoe & Suburban - FOR THEM WHO WANTS TO DISABLE THERE DRL - This may help if someone wants todisable DRL Option Document ID: 2022756 [hr] [/align]#PIT4328A: DRL Disable Procedure - keywords daytime disable headlights headlamps lamp light - (Oct 2, 2007) [/align]...

chevroletforum.com

The problem:

When I'm in daytime shade, the dash is dimmed. Takes about 20 seconds after pulling into direct sunlight before the dash finally brightens. Need to bypass dimming so it turns on with headlights only..

Sounds like a simple resistor won't cut it. Anyone have some ideas? I'll eventually pull the sensor to see what happens..

 

[mikez71]

Ambient Light Sensor Override (Take Your Brightness...

www.coloradofans.com

According to that link, grounding the sensor wire should keep dash bright.. Looking at out wiring diagrams, it's a white wire that goes to BCM X2(J2?) pin 11. Ground is a white/black wire.

Have it disconnected, don't see any white goop. Sunload sensor wiring is L-BU/BK and GY
Might wire a relay powered by headlight output to connect ambient sensor.. no headlight have it go through 600ohm resistor mentioned in the first post link.

 

[swathdiver]

Do you have a dash mat or something obstructing the sensor? Mine switches pretty quick even with the dash mat around it. The sensors are very reliable but have seen them wear out over the years.

 

[mikez71]

No dashmat. Probably should try a new sensor, don't want to add wiring for something like this. I don't notice it that often, relatively minor annoyance, but I am hoping it's one of the last little electrical "fixes" I will make to this truck..

Disconnected sensor and backlighting is daylight bright.(makes sense safety wise) Dimmer circuit will not adjust instrument/radio display backlighting, but still adjusts switch backlighting.

 

[Airman68]

Mine seems to be "lazy". Takes a long time once outside to brighten up. Somtimes while driving, it dims the dash lights for no reason. Wonder if I should just change the sensor??

 

[mikez71]

Somtimes while driving, it dims the dash lights for no reason.

That's what gets to me. Even if there is a reason (tunnel/trees) I do not want it dimmed in daytime! Still hoping to bypass, but I haven't worked on it lately as I am trying to glue the cracked dash together.. Using lots of JB weld..

BTW what year is yours? I've seen posts about white goo inside the sensor, doesn't look like it's in mine, but maybe I need to take it apart to see it..

 

[Scott in AZ]

My ambient sensor is failed so my headlights are on all the time, and DRL are never on. I’m getting psyched up to remove the dash, paint it with a Pewter refresh, and replace the ambient sensor.

I think if you ground out your sensor, your DRLs won’t work, and you’ll have same problem as I do.

Then the only other electrical gremlin I’ll have is the fuel gage. My level sensor is starting to fail. Fuel Gage measures accurately below 3/4 tank but intermittent goes to “E” empty when full. I’ve heard I need to replace the fuel pump to fix this.

 

[Foggy]

My ambient sensor is failed so my headlights are on all the time, and DRL are never on. I’m getting psyched up to remove the dash, paint it with a Pewter refresh, and replace the ambient sensor.

I think if you ground out your sensor, your DRLs won’t work, and you’ll have same problem as I do.

Then the only other electrical gremlin I’ll have is the fuel gage. My level sensor is starting to fail. Fuel Gage measures accurately below 3/4 tank but intermittent goes to “E” empty when full. I’ve heard I need to replace the fuel pump to fix this.

Try running 2 bottles (big ones) of Techron Fuel System Concentrate in
your next fill up. Might take 2 tries... This is pretty common on the early 2000+
GM stuff. Shit gets built up on the sending unit. Techron will fix it most of the time..
if it does, make sure to run the techron thru regularly (only use the black bottle that says
Concentrate) , the other ones suck

 

[Scott in AZ]

Try running 2 bottles (big ones) of Techron Fuel System Concentrate in
your next fill up. Might take 2 tries... This is pretty common on the early 2000+
GM stuff. Shit gets built up on the sending unit. Techron will fix it most of the time..
if it does, make sure to run the techron thru regularly (only use the black bottle that says
Concentrate) , the other ones suck

Foggy if this works Ima’ come correct w you. Thanks already. I’ll give it a try and let you know.

 

[Airman68]

That's what gets to me. Even if there is a reason (tunnel/trees) I do not want it dimmed in daytime! Still hoping to bypass, but I haven't worked on it lately as I am trying to glue the cracked dash together.. Using lots of JB weld..

BTW what year is yours? I've seen posts about white goo inside the sensor, doesn't look like it's in mine, but maybe I need to take it apart to see it..

Mine is a 2008. Still trying to work out some bugs and this one bugs me...

 

[Airman68]

My ambient sensor is failed so my headlights are on all the time, and DRL are never on. I’m getting psyched up to remove the dash, paint it with a Pewter refresh, and replace the ambient sensor.

I think if you ground out your sensor, your DRLs won’t work, and you’ll have same problem as I do.

Then the only other electrical gremlin I’ll have is the fuel gage. My level sensor is starting to fail. Fuel Gage measures accurately below 3/4 tank but intermittent goes to “E” empty when full. I’ve heard I need to replace the fuel pump to fix this.

If it's the same as the trucks, yes, the fuel pump and sending unit are all together. Trucks are easier because you can lift the bed and get to it. Guessing the tank will need to be lowerd on these for replacement.

 

[mikez71]

Any possibility it's the cluster? (Might be worth checking so you don't have to drop the tank)
Or it maybe a good time to put a new fuel pump in anyway..

For light sensor, I'm thinking about using a relay like this..

https://www.amazon.com/HiLetgo-Channel-Isolation-Support-Trigger/dp/B00LW15D1M/ref=asc_df_B00LW15D1M/?tag=hyprod-20&linkCode=df0&hvadid=167156423255&hvpos=&hvnetw=g&hvrand=9282882679990221483&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9032424&hvtargid=pla-343992463804&psc=1

Wire it so sensor is connected when headlights are on. (So it dims at night and dimmer adjustment works, otherwise daytime it's full brightness no dimmer control)

But you still need a sensor that works..

 

[mikez71]

quick test seems to show

15k ohm resistance in dark area
500 ohm resistance in direct sunlight.

Makes sense why GM tells you to wire in a 600ohm resistor to disable auto headlights.

(white wire is signal and black/white is ground)
Thinking I might wire those pins to a relay and resistors..

 

[Foggy]

Foggy if this works Ima’ come correct w you. Thanks already. I’ll give it a try and let you know.

It's the sulpher in the fuel that builds up on the sensor. C5 corvettes are really bad about this..
but it applies to a bunch of diff vehicles. Hope it works for you !!

 

[mikez71]

Little update, a 10K ohm resistor will put the interior lights into night mode. Dimmer can adjust!
Next step is to wire up a relay so when lights turn on, interior lights will dim.

UPDATE: I used a 680ohm for daytime, 10k ohm for switched using a switching (SPDT) relay and wired the relay trigger to the park lamp circuit (brown wire, but I used the trailer park lamp fuse) Still about a 3 second delay before display dims when turning on lights, I guess that is programmed so the display isnt dimming at every little shadow..

IMPORTANT: Without a diode, there is a voltage spike that will cause your BCM to turn off the display backlighting for a second when turning off the lights (and therefore the relay)
So make if you do this, you get a relay with diode built in, or wire one yourself to the coil connections on the relay.

 

[mikez71]

update2: well maybe its not a reverse voltage spike.
Installed a relay with diode, and when turning headlights off, the gauge backlighting still turns off for 2-3 seconds before turning back on in daylight setting.
The dic display does not have this quirk, only the gauge lighting. Also does it when I disconnect the daytime resistor and leave that circuit open (simulating a missing light sensor)
Reverted back to the sensor for now, afraid the signal is bad and I might fry something.

If anyone has an idea why the BCM would turn gauge backlight off for a couple seconds, when turning off lights and switching from 10k ohm to 680 ohm resistor on the light sensor to ground circuit, please let me know! Wiring diagram says it is an analog/digital pull-up

UPDATE: When the headlights and auto lights are off (with the stock ambient light sensor), and it is dark outside, the gauge backlighting is off. I believe that is the reason my gauge lighting would go off as I changed from lights on to lights off, the 3 second delay before changing backlighting modes. It would first change from nighttime mode/lights on to nighttime mode/lights off, before finally changing to daytime mode. Will re-install the relay in the near future.