Option #1:
By: Jeffoto - Reatta Forurm member
I decided to try the Photocell from a replacement photocell used for 120v 300 watt outdoor lights. (Home Depot, $7.90, UPC 046335834811)
The photocell in the Buick is housed in a plastic holder that pops into place like a light bulb. When removed from this housing and replaced with a new photocell from Home Depot it works well. The only downside is that it works too well and not only must you break off the blue top of the holder to let in enough light (the dash is dark enough during the day to trip it) and when it is dark the reading is higher than it needs to be so it will trip the B119 error code (photocell circuit error) but it wont hurt anything and works great!
Just be careful when pulling apart the dash. (center grill comes out first, three torx screws, and seven metal pull clips on the front (side closest to seats) should be lifted with a L shaped to to remove straight up to avoid cracking the dash)
Just so everyone knows, the reading in the BCM data for photocell must read 74 or more to put car into night mode.Option #2:
By: KDirk - Reatta Forurm member
I have some good news on sourcing a new photocell - and cheaply at that. The photocell assembly is a blue plastic carrier that is flat on top and has a wedge base much like that of the light bulb used for the foot well courtesy lamps. A CDS photocell with wire leads is than "wrapped" around the wedge base to make the contacts that go into the socket that twist-locks into the dash under the trim pad.
On a hunch, I went to Radio Shack and bought an assortment bag (#276-1657) of CDS photocells (had two large, two medium, and two small) for under $5. I used one of the large - about 1/4" diameter face - parts and wrapped the wire leads onto the blue plastic carrier (no polarity to worry about) just as the old one had come off. Put it in and tested it, and voila! I now have a working photocell that reads 98 when fully darkened, and around 17-18 in daylight (with the dash pad off anyway).
This was an easy fix, the toughest part was getting the dash pad off to get to the sensor assembly underneath. Better still is that I have enough parts to do another car for no additional cost. I may try one of the medium ones to see if it works as well. If so, I could replace 4 sensors for under $5 total - quite the deal if I may say. I suspect the smallest one is not up to the job, though it may well work.
Best part is that it negates the need to go and buy a hardware store dusk to dawn sensor and gut it for the photocell. Just thought I'd pass this along. One other note: be sure to clean the top (face) of the blue plastic lens to get off the accumulation of dust that will be on it before reinstalling.
Thanks to members of the Reatta forums for this information.
