Gentex 261 Mirror Repair

I have a similar problem with a similar mirror, maybe someone can shed some light on it? My mirror, a Gentex 177 stopped working all together. When I test it off the vehicle, it works IF on a 16 volts power supply, but is completely dead on a 12 volt one. Any idea what could cause that? maybe a bad capacitor or something? Any ideas or thoughts on where to start looking for a bad component? Thanks everyone.

pgethea, Without a circuit schematic, it's going to be a problem trying to find the component causing the problem. You might follow (trace) the +12 VDC circuit, and see where it is converted to +5 VDC, or whatever is used on the Temperature Circuit Board. I'd suggest looking on Ebay for a replacement Mirror and just plug it in. But, I know exactly how you feel because I opened mine up to see what was causing my problem. I was lucky and found the COLD/BAD solder joint. You might be as lucky, and have the same type problem. I elected to not trace any of the circuits when I opened mine. Larry

Thanks for the reply. I already bought another one, but while I wait for it, I am thinking of ways I might be able to debug this one. If it was dead I would be fine trashing it, but it works, it just needs a higher voltage to work. I was hoping someone might have seen this before and have an idea of what to look for. I already opened it up and didn't see anything obvious wrong with it, but I will more carefully today. Why do you think I should try to trace the 12V to the temp control board? my mirror is completely dead with 12V, nothing works,so the problem is not isolated to the temp control board. Thanks.

THIS IS EXACTLY WHAT WAS WRONG WITH MY MIRROR!!!!! THANK YOU!!!!!!!

Your posts are the kind that keep on giving months and months later. I too am having issues with my RV mirror. I conducted the TS described above on a GNTX-261 and I am starting to suspect that I may have a defective mirror rather than a power supply issues. However, it works intermittently so I am not sure if there is an another circuit giving me grief. How does one tell which model of GNTX-261 is installed? My mirror has the 16 pin connector with compass/temp/airbag and dimmer, it does not have On-Star. When looking for a replacement, all I can find are the units with On-star. Also, what is the device that is separately mounted on the windshield mount? It is connected to the mirror via a 2 pr wire. None of the wiring diagrams seem to show it. the diagrams show the temp sensor, which is located behind the grill of my truck. Symptoms: Upon start up and boot, the unit displays temp and direction; airbag status (on/off) is indicated. after a few minutes, the temp/comp dims or goes out but the airbag indicator stays lit. After a while, the unit does dark. Occasionally, the temp/comp digits start flashing random symbols. It looks like all cells of the display are firing off all at once. In the meantime, the airbag indicator is constant and not flashing. Is this an indicator of unit failure or could it be a fault in the temp sensor? I'd hate to spend the $70 on a new mirror only to find its the sensor. Any Ideas? BTW: I have a 2004 Chev Silverado 4wd Z71 with extras. In gratitude of your knowledge,

Pacrim

I don't think there is an eay way to know, other than the different buttons on the front side. All units have the number molded in the plastic case. GNTX-261 But, that is only the Model Number of the Mirror. It doesn't tell you the features it has. If your unit is for an RV, the Cad Cell might be remote mounted, to auto dim the Mirror. Does your Mirror have a hole on the left side pointing towards the front of the vehicle that dims the mirror when covered and the mirror is powered? If not, I suspect they remote mounted tha cad cell. Larry

Just when I thought I had the answer... Thanks for the model id discussion. On previous post, I discussed how I tested the mirror and suspected that the unit has a fault in it. As of last night, I have revised my suspicion that it may not be the mirror but rather something going on in one of the vehicle's control modules. Condition & Symptom: Parked, motor off, ignition on. Mirror not working, compass and temp out, airbag indicator lit. (this is were it gets odd) I activate the power windows to close the windows and the compass/temp light up with accurate heading and temperature. When I release the the window switches the mirror stops working. Activate the window switches again, mirror works, release switch, mirror goes dark. Repeat, same result. I guess the good thing is I now suspect that the mirror may not need replacing.       Any suggestions?In gratitude of your knowledge,

Pacrim

pacrim, Afterlooking at my mirror, I'm thinking that you are referencing the cable that runs from the Mirror to the Base Unit. That is the GPS Locator Circuit Board, and is attached to the base, so it can receive the GPS Satellites. Larry

pacrim, UMmmm...CHEVY...Have you ever seen the "SERVICE BRAKE SYSTEM" Fault light when you start your Silverado? I've got a 2003 Duramax, and there was a grounding problem that I finally fixed. I kept getting that error message about every 8 months to a year, intervals. Mine had a bad GROUND directly under your Left Foot as you sit in the seat. The Ground for the EBC is attached to the Frame there. I had cleaned, scraped, and re-tightened that connection several times, but that didn't fix it. I finally got a Star Washer and put between the Frame and the Lug. That finally fixed it. Now, none of my Dash Instruments work for 2-3 minutes after I start the truck. DAD BURN CHEVY's. I always seem to have all the troubles. Larry

Larry - I stumbled upon this forum while searching for a replacement mirror for my 2003 Tahoe. The mirror compass and temperature was no longer displaying, but the airbag ON/OFF was. I cracked the enclosure and sure enough - the same resistor had a crack in the solder - it was no longer connected on one side. Dropped a little solder in there and hooked it up and it is working again. Thanks a ton for taking the time to post your pictures and your fix!