Electrochromic automatic dimming mirrors

Chevy Tahoe LS 2002: My electrochromic automatic dimming mirrors suddenly do not turn ON when restarting the vehicle. I can turn them ON by pressing the button on the mirror for 6 seconds, but when I turn off the vehicle and restart, they are OFF again.

How do I set them so they will be turned ON when I start the vehicle, as used to be the case?

What does your owners manual say?

It says nothing about manually setting them. It says that the dimming mirror mechanism will turn ON when restarting the vehicle. Although that used to be true, it is no longer the case.

If I was dispatched this job I would first verify that what you want the mirrors to do is something they are designed to do then if no theory of operation was explained in the FSM it would be time to get the schematic out and do some analysis.

Does this vehicle have a menu you can access as part of the electronic driver information system? (or whatever GM calls the display you have that shows temp, door ajar, etc.) If so, I’d suspect that somewhere a config setting got changed buried somewhere in the menu system, either inadvertently by you, or by whatever gremlins randomly change things like this. If you can find such a setting and it’s already set how it should be, you can try the old Windows trick of changing the setting, exiting, then changing it back.

If none of the above works, I’d suspect you have a computer problem, and it may just be cheaper and easier to live with it than try to track it down. Having the software ‘flashed’ to a newer version if available by the dealer may help though.

On my 2000 Impala the auto dimming mirror STB (All the fluid leaked out)so now it is no longer a auto dimming mirror. Its one of those thing I will not worry about fixing.