I checked things out with the Tech 2 but other than the voltage of the sensor there wasn't anything else to check. I didn't check the FSM to see if it gives some reference/expected voltages in various conditions so I have no clue what normal is.
9:41am, 1.67V. I think at this time it was satisfied that it was daylight.
I didn't see any kind of calibration option so I did the reasonable thing and just ordered a new sensor. Rockauto stocked it. About $30 shipped for a real GM sensor.
https://www.rockauto.com/en/moreinfo.ph ... 59&jsn=775
Applications include:
BUICK ALLURE 2005-2008
BUICK ENCLAVE 2008-2015
BUICK LACROSSE 2005-2009
BUICK LESABRE 2000-2005
BUICK LUCERNE 2007-2011
BUICK RAINIER 2004-2007
CADILLAC CTS 2003-2015
CADILLAC DEVILLE 2001-2005
CADILLAC DTS 2006-2011
CADILLAC ESCALADE 2003-2014
CADILLAC SRX 2005-2009
CADILLAC STS 2005-2011
CADILLAC XLR 2004-2009
CHEVROLET AVALANCHE 2007-2013
CHEVROLET AVALANCHE 1500 2006
CHEVROLET AVALANCHE 2500 2003-2005
CHEVROLET CAPRICE 2011-2013
CHEVROLET CAPTIVA SPORT 2012-2015
CHEVROLET CORVETTE 2005-2013
CHEVROLET MALIBU 2004-2012
CHEVROLET SILVERADO 1500 2003-2013
CHEVROLET SILVERADO 1500 CLASSIC 2007
CHEVROLET SILVERADO 2500 2003-2014
CHEVROLET SILVERADO 2500 CLASSIC 2007
CHEVROLET SILVERADO 3500 2003-2014
CHEVROLET SILVERADO 3500 CLASSIC 2007
CHEVROLET SSR 2003-2006
CHEVROLET SUBURBAN 1500 2005-2014
CHEVROLET SUBURBAN 2500 2003-2011
CHEVROLET TAHOE 2003-2014
CHEVROLET TRAILBLAZER 2002-2009
CHEVROLET TRAVERSE 2009-2017
GMC ACADIA 2007-2016
GMC ENVOY 2003-2009
GMC SIERRA 1500 2003-2013
GMC SIERRA 1500 CLASSIC 2007
GMC SIERRA 2500 2003-2014
GMC SIERRA 2500 CLASSIC 2007
GMC SIERRA 3500 2003-2014
GMC SIERRA 3500 CLASSIC 2007
GMC YUKON 2003-2014
GMC YUKON XL 1500 2003-2014
GMC YUKON XL 2500 2003-2013
HUMMER H2 2003-2009
ISUZU ASCENDER 2003-2008
OLDSMOBILE AURORA 2001-2003
OLDSMOBILE BRAVADA 2002-2004
PONTIAC BONNEVILLE 2000-2005
PONTIAC G6 2006-2009
PONTIAC G8 2008
PONTIAC GRAND PRIX 2005-2007
SAAB 9-7X 2007-2009
SATURN AURA 2007-2009
SATURN OUTLOOK 2007-2010
SATURN VUE 2009
SUZUKI XL-7 2009
Oddly, the oldest application is a 2000 H-body (LeSabre/Bonneville). It was used as a recently as a 2017 Traverse. Wow. 2003-2015 CTS. This is a lot of stuff.
It is in the front/center of the dash. The instructions were pretty simple. Just pry the long plastic piece up carefully. There are 6 clips. The diagram helped me understand about where they were so it was simple to pry with my plastic trim tools. Got the trim piece up, gave the sensor like a 1/4 turn to loosen, disconnected plug, plugged in new sensor and 1/4 turn the new sensor into the trim panel. It is keyed so I had to study it for a second. Carefully replace the trim panel and clip everything back down. Nothing broke. Also take a look at the BOSE center speaker. Perfect condition as usual.
This was at most a 15 minute job.
Old sensor on right (load image to see it properly - this forum still ignores EXIF rotation data). The cover is more transparent. Old sensor made in Philippines and new made in Lithuania.
Ed borrowed the Tech 2 so I can't check the voltage. I did turn the key on and the headlights came on (it was 10:47am) but shortly after I took the car to get gas. The lights were off the whole time. I mean, I can't imagine what other issue there would be other than like the module this goes to or wiring. I doubt either of those things are a problem because the lights WOULD shut off, it just required very bright conditions.
I'll report back if something is still funky but I suspect this is finally fixed!