Light sensor - 2008 Z51 Coupe
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Pro
Joined: Jul 2004
Posts: 713
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From: Waterford CT
Light sensor - 2008 Z51 Coupe
I backed out of my garage this morning and the headlights were automatically on as per usual. However, after driving out in the bright morning sunshine they would not turn off. I shut the lights off with the switch on the stalk which brightened up my displays so I could see them in the light of day, but doing that sets a "headlights recommended" message on the DIC which will not go away so I do not have visibility to any of the other good info that I have there. It appears to be a failed light sensor on the top of the dash. I had one of these go while under warranty on a Pontiac a few years ago so this is not unknown to GM.
Does anyone out there in forum land have any experience with the sensor failing? How bad is it to change the thing? It looks like the whole top of the dash has to come off and I HATE doing interior work. Suggestions are welcome.
Thanks,
Paul
Does anyone out there in forum land have any experience with the sensor failing? How bad is it to change the thing? It looks like the whole top of the dash has to come off and I HATE doing interior work. Suggestions are welcome.
Thanks,
Paul
Melting Slicks
Joined: Dec 2013
Posts: 2,232
Likes: 315
From: Bridgewater New Jersey
I do not have first hand experience with replacing the light sensor, but it may come out once the center console and radio assembly is out, thinking out load.....
OK.... Found a video on how to replace the photocell sensor, apparently real easy..
OK.... Found a video on how to replace the photocell sensor, apparently real easy..
Last edited by extrapilot; Jun 13, 2016 at 07:49 PM.
Melting Slicks
Joined: Dec 2013
Posts: 2,232
Likes: 315
From: Bridgewater New Jersey
Yeah, I also experience a great length of delay when coming from a dark environment, and it seems that the sensor needs to see a good amount of daylight to engage daytime operations. This could be the issue here also with Paul's car....
Melting Slicks
Joined: Dec 2013
Posts: 2,232
Likes: 315
From: Bridgewater New Jersey
Race Director
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IIRQ, the sensor is wired through the A/C control module.
So on that note, before you do anything, disconnect the battery for a few mins to reset the entire car/allow the A/C control module to hard reset.
Hence it not uncommon for the car modules to glitch once in a while and the fastest way to solve the glitch problem in them, is to just hard reset them with a battery disconnect for a few mins.
Note, when you reconnect the battery, don't forget to reindex the windows.
So on that note, before you do anything, disconnect the battery for a few mins to reset the entire car/allow the A/C control module to hard reset.
Hence it not uncommon for the car modules to glitch once in a while and the fastest way to solve the glitch problem in them, is to just hard reset them with a battery disconnect for a few mins.
Note, when you reconnect the battery, don't forget to reindex the windows.
Melting Slicks
Joined: Dec 2013
Posts: 2,232
Likes: 315
From: Bridgewater New Jersey
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The Ambient light sensor is wire through the A/C controller,
The A/C controller sends 5 volts to the Ambient sensor, then reads the voltage back through the sensor to tell the Ambient light conditions.
It them tells the BCM via the GM land bus the Ambient light conditions/if the BCM needs to turn the lights on or off.
Hence the A/C controller is the closest active module to the sensor and why it was put in play for that sensor.
Note, it kind of like the steering wheel sensor, which is wired directly to the EBCM, which the ECM gets it's information from it via the GM land bus a well.
So, if the A/C controller has a glitch reading the sensor, or is not putting a full 5v out to the sensor to get back the correct reading to begin with, the car will have problems, even if the Ambient light sensor is still good.
The A/C controller sends 5 volts to the Ambient sensor, then reads the voltage back through the sensor to tell the Ambient light conditions.
It them tells the BCM via the GM land bus the Ambient light conditions/if the BCM needs to turn the lights on or off.
Hence the A/C controller is the closest active module to the sensor and why it was put in play for that sensor.
Note, it kind of like the steering wheel sensor, which is wired directly to the EBCM, which the ECM gets it's information from it via the GM land bus a well.
So, if the A/C controller has a glitch reading the sensor, or is not putting a full 5v out to the sensor to get back the correct reading to begin with, the car will have problems, even if the Ambient light sensor is still good.
Melting Slicks
Joined: Aug 2004
Posts: 2,914
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From: Oakbank Manitoba
The light sensor is actually dual purpose. It has two internal sensors that are used for the dual zone A/C. The A/C system monitors the sun intensity and direction in it's calculations.
Actually the TPMS module is located closer to the light sensor.
Actually the TPMS module is located closer to the light sensor.