Nothing life-threatening...Just curious

I have a '99 Silvey and it has the "power rear-view mirror." As far as I knew it only had the auto-dimmer/compass combo but for some strange
reason I just noticed last night that when I first started the truck the whole display lit up allowing me to see that it also had the ability to display temperature. This feature would be of much better use to me but I don't know how to engage it. The only buttons on the mirror are COMP and MIRROR. I tried pressing down on each button to see if it would scroll through the options but each one only turned off the certain feature. When I pressed them both down at the same time it started counting numbers from 1-15. Is this some other kind of setting too or did I just reprogram the whole thing. Like I said, this isn't such a big deal but it was just something I was curious about. Heck, maybe someone else was wondering the same thing. Thanks in advance.
In Christ Alone
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The temp feature doesn't work on the '99 models. Although the mirror is set up for it, the rest of the truck isn't. Should have bought a '00. :/
Dave
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