Reatta45 Posted October 29, 2005 Share Posted October 29, 2005 You have an excellent forum here ? wish I had some of this information six years ago?Can anyone tell me what photocell will replace the cell in the twilight sensor? Or can you give me it?s resistance in sunlight and the resistance dark. I did find a very nice, 2002 post by cdoersom, His thread ?Twilight Sensor? looked to be exactly what I was looking for, but the part # was not included and I have had on luck in contacting him with direct email or PM. My ?91 failed and I replaced the cell with a fixed resistor, this allows the instrument panel to dim with IP dimming circuit but I would like to replace the photocell and get it back closer to 100%, then I?m only short the sunroof cables to have everything as should be? Thank you for any information that might get the right cell. KennyV. Link to comment Share on other sites More sharing options...
Jim Posted October 29, 2005 Share Posted October 29, 2005 I have several Reatta parts cars and have a good twilight sensor/photo cell assembly available. I can be reached at jfinn@cpinternet.comI do not have and good sunroof cables available at this time but they are available new from your Mazda dealer. Just order them for an '89 RX7 Link to comment Share on other sites More sharing options...
Machiner 55 Posted October 30, 2005 Share Posted October 30, 2005 Hello Jim,Do you know how to check the photo-cells to see if they are good or not? If so, how is it done? Link to comment Share on other sites More sharing options...
Guest cdoersom Posted November 4, 2005 Share Posted November 4, 2005 I haven't had a Reatta in a while, so I can't check the part. I bought a few of the sensors and should have some left, but I can't find them amongst all my junk. Anyway, I bought the parts from All Electronics for about $0.75 each. I think it was part number PRE-23, but can't verify. I looked it up on their web site and they are out of stock. What I do remember is that it's called a Photoconductive Cell and has a high resistance when dark and a low resistance when light. And that's how you test it - cover the sensor and the resistance should be high, shine a bright light on it and the resistance should be low. The catalogue says that the high resistance is about 50K ohms and the low resistance is 100 ohms. If someone could test their sensor and verify this it would help.You might be able to find these from other electronics parts vendors. If I stumble onto my stash of sensors I'll let you know.Chuck Link to comment Share on other sites More sharing options...
Reatta45 Posted November 4, 2005 Author Share Posted November 4, 2005 Chuck, Thank you for your efforts let me know if you locate the parts or part#s. KennyV. Link to comment Share on other sites More sharing options...
Machiner 55 Posted November 6, 2005 Share Posted November 6, 2005 After exhausting all the leads I could think of ie. the Internet, Radio Shack the local electronics supply store (who, I might add, looked through a couple of Bible sized catalogs for the little buggers) I gave up trying to locate a source for a new replacement. I went to one local salvage yard and was able to round up half a dozen cells. Don't ask what I paid for them 'cause I don't know. I salvaged several items and purchased them as a group. I can say that they cost next to nothing.Try as I might, I couldn't come up with a definitive test for the Photocells. All I can say is, that when connected to an auto-ranging multi-meter, and placed in absolute darkness (inside of my upside down slipper, under the computer desk, with only the glow of the monitor for illumination) for approx. 15 minutes, the cell that I suspected was bad read high resistance on the "k" ohms scale. The others (not "The Others") that were taken from the salvage yard, when tested the same way, would read high resistance on the meg-ohm scale. As EDBSO mentioned in another thread, there is a test in the manual and he has provided a link to another test from yet another thread. Link to Post/Thread here. You can also do a search using "photocell" as the keyword and "DTerry " for the username and come up with some good info. One of these days I'll get around to attaching photos of the dash and photo cell location. (and my damaged dash) It amazes me that I was able to get the cells out of the salvage yard autos without much difficulty but, on my own car, I had to fight like heck to get that bad boy out. Link to comment Share on other sites More sharing options...
Jim Posted November 7, 2005 Share Posted November 7, 2005 I have to agree with 88 89 Reattajohn on the resistance values of the twilight sensors not being in the 500 to 1K ohm range.With my Fluke digital ohmmeter I checked 7 used sensors, the results were---5K-7K, 10K-15K, 10K-16k, 175K-1.5M, 265K-3M, 350K-3M and 400K-4M ohms.I do not know what is correct but will do some testing in one of my cars to see which ones work and which ones don't work. There is a test proceedure in the shop manual that can be done on a car with a touch screen and you can check voltages to see if the sensor is working. The test is in section 8A-88-5 Table D. Link to comment Share on other sites More sharing options...
manikmekanik Posted November 7, 2005 Share Posted November 7, 2005 I've found the plastic dash parts are less likely to snap or break when removed from a car sitting in the sun, and parts are warm. The solar radiation warms and softens the parts, unlike the parts warmed without sun, as in a heated garage.Did you find any Reattae in your boneyard hunt? Link to comment Share on other sites More sharing options...
Machiner 55 Posted November 7, 2005 Share Posted November 7, 2005 No salvage yard within a 10 - 15 mile radius from where I live have any Reattae.At the particular salvage yard I was at a couple of days ago (Pauls Auto Yard) it's even getting hard to find Rivieras from which to get parts. A few months ago there were three or four. Now, there is only one and it was a recent aquisition. The others have been crushed. I'm going to have to scramble to get what I can before it and the two Trofeos are history. These guys got the best prices in the area. Especially if you pull the parts yourself. Link to comment Share on other sites More sharing options...
Guest F14CRAZY Posted November 8, 2005 Share Posted November 8, 2005 Gee, it's like we have to start raiding junkyards and creating caches of parts from these Rivis. A friend of my dads bought an '88 that ran and drove for like $75 and parked it behind my dads shed at the own property he owns. We've robbed the CRT and IPC and I really should go back for those switches. We also once got the ECM and BCM out of it, by hand and 2x8s Link to comment Share on other sites More sharing options...
Machiner 55 Posted November 8, 2005 Share Posted November 8, 2005 Yah, better stock up or we'll be at the mercy of Jim and Manik. (Just teasing guys. Don't nobody be get'n all uppity now.) Link to comment Share on other sites More sharing options...
Guest cdoersom Posted November 10, 2005 Share Posted November 10, 2005 When I was testing the photocells and trying to find a replacement, I put a rheostat in place of the sensor in the car and then watched the values change on the computer screen using the test on page 8A-88-5 as mentioned previously by Jim. This way you can find out the range that the car is looking for and then find a suitable replacement in an electronics catalog, or at least devise a test for used sensors to see if they are good.Chuck Link to comment Share on other sites More sharing options...
Guest F14CRAZY Posted November 10, 2005 Share Posted November 10, 2005 When I fill in someone that's not familiar with Reattas, I can tell them how we discuss online how to replace the little light sensor in the instrument panel Link to comment Share on other sites More sharing options...
Reatta45 Posted November 12, 2005 Author Share Posted November 12, 2005 Thanks to all that have replied to this thread? Just installed the photo cell that I received from Jim? Its working perfect. It has a dark resistance of 2meg and a reading of around 110k in light. Now that I have a working cell I will try to find a suitable substitute. I will post back should I find anything promising. KennyV Link to comment Share on other sites More sharing options...
Guest cdoersom Posted November 16, 2005 Share Posted November 16, 2005 Here might be a source of supply. Here's the specs on various photocells - it looks like the Silonex NSL-4950 might be the closest fit. Silonex And it looks like Allied Electronics has it in stock for $2.05 each. Allied Electronics Chuck Link to comment Share on other sites More sharing options...
Reatta45 Posted November 16, 2005 Author Share Posted November 16, 2005 Chuck? Nice find, I?ll have to round up a light meter, remove my photo cell and do some bench work? Thanks, KennyV. Link to comment Share on other sites More sharing options...
johnymac Posted July 24, 2006 Share Posted July 24, 2006 I have a 1991 Riviera, bought several months ago with several electrical problems.I previous owner had an estimate from a local Buick dealer stating it was the BCM. I replaced that and the light switch, over $300.00 worth, for nothing.After many hours and wire tracing I found that I too have a defective Photocell.I am in New England and can't find many Rivera in the junk yard in a 25 mile radius.I have called around and can not find a replacement at the dealerships.I have checked a few of the electrical stores listed above, no luck.Does anyone know where I may find one?I would also like to ask how these are replaced. I have half my dash apart so that the sensor, the brown plastic piece is to a point where I can get a jumper into the bottom so as to cross the wires.Not sure if the sensor goes into this housing or if I need to get these wires out.I figure I should ask in case I find one at a junk yard someday, if I take a road trip.Thanks very much to anyone that replies. Link to comment Share on other sites More sharing options...
Guest DTerry Posted July 24, 2006 Share Posted July 24, 2006 Lotsa GM cars used the same photocell as the Reatta, and I assume the Riviera is the same. I picked up a couple at my local junque yard. Link to comment Share on other sites More sharing options...
johnymac Posted July 26, 2006 Share Posted July 26, 2006 The dealership I called told me only 1986-1993 sensor would fit.I will have to check to see what else will fit.So.....I would also like to ask how these are replaced. I have half my dash apart so that the sensor, the brown plastic piece is to a point where I can get a jumper into the bottom so as to cross the wires.Not sure if the sensor goes into this housing or if I need to get these wires out.Can someone tell me the best way to replace this sensor??Thanks much!! Link to comment Share on other sites More sharing options...
Guest DTerry Posted July 26, 2006 Share Posted July 26, 2006 The blue thingie on top of the brown thingie is the photocell. It just plugs in. Link to comment Share on other sites More sharing options...
Guest DTerry Posted July 26, 2006 Share Posted July 26, 2006 Well, that didn't work out too well. I'll try it again. Link to comment Share on other sites More sharing options...
Guest DTerry Posted July 26, 2006 Share Posted July 26, 2006 Incidentally that photo was pirated, and I'd give credit except that I don't remember from whom it was pirated. <img src="http://forums.aaca.org/images/graemlins/wink.gif" alt="" /> Link to comment Share on other sites More sharing options...
Machiner 55 Posted July 27, 2006 Share Posted July 27, 2006 Blue thingy out of it's holder and photocell out it's blue thingy. [color:"red"] See Attached. Link to comment Share on other sites More sharing options...
johnymac Posted July 29, 2006 Share Posted July 29, 2006 Thanks guys.The sesnor came out really easy.Took a 2.5 hour ride to large salvage yard.Got a sensor out of a 92. After all that, it doesn't work, even with the wires jumped as the old sensor would dim the dash this way. The numbrs are diffeent on them.I will try to test them tomorrow.So still at this. Any idea where these can be purchased these days?Thans again... Link to comment Share on other sites More sharing options...
Guest F14CRAZY Posted July 29, 2006 Share Posted July 29, 2006 If you knew the resistance of the photocell, couldn't it be had from an electronics supply store? Link to comment Share on other sites More sharing options...
johnymac Posted July 30, 2006 Share Posted July 30, 2006 I'm having a problem getting a reading with my cheapo voltmeter.This may be a stupid question, but does the sensor and the capacitor have to be change together, as a set? Thought I would ask, the sensor I picked up has a different capacitor.Thanks. Link to comment Share on other sites More sharing options...
johnymac Posted July 30, 2006 Share Posted July 30, 2006 My readings sure don't look like the ones above.The orginial one from the car was:dark reading 2.1 at 200k ohms or 420klight reading 1.6 at 200k ohms or 320kThe one from the salvage yard:dark reading 16.1 at 200k ohms or 3Mlight reading 3.3 at 200k ohms or 660k Link to comment Share on other sites More sharing options...
Guest DTerry Posted July 31, 2006 Share Posted July 31, 2006 Johnnymac:No. The "capacitor" is a "thermistor" (whatever that is) that senses sun load to determine A/C cooling requirements. An anticipator of sorts, and has nothing to do with light dimming. Just mounted on the same bracket. Link to comment Share on other sites More sharing options...
johnymac Posted August 1, 2006 Share Posted August 1, 2006 Wishful thinking on my part.I will have to keep searching for a sensor.New problem, I have taken the sensor out and have the wires jumped.I have dash lights now when the car is off and when I turn it on they go out.Got to love electrical problems.I shall continue my search.Thanks to all! Link to comment Share on other sites More sharing options...
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