[91chevZ71]

thanks, ss

-edit
got this from another forum ( I think it was like 12voltpower or something, whoknows)

again, this is not my work and I have not tested it yet (but I will). I'll follow this when my 16-pin mirror gets here and let you guys know

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After reading all the other posts in this thread and comparing the wiring data, here's a more complete list:

Pin 1-not used
2 - Microphone (if the mirror is equipped with it)
3 - "Passenger Air Bag on" notification (if mirror is equipped with that display) - ground pin to activate icon
4 - "Passenger Air Bag off" notification (if mirror is equipped with that display) - ground pin to activate icon
5 - auto day/night signal, which comes from the LH outside rearview mirror
6 - Temp probe connection ( if mirror is equipped with display)
7 - Temp probe connection (if mirror is equipped with display)
8 - Ground
9 - After taking a mirror apart and experimenting, I've discovered that pin 9 is common with pin 8 - they are both soldered directly to the ground plane on the circuit board. So, it's a ground.
10 - Microphone (if mirror is equipped)
11- keypad signal (out) for On-star - pressing any button puts out a multiplexed signal on this pin, - so you can't just use the buttons to control whatever you want to. Sorry.
Update - Well, yes you can, if you do a little rewiring (arghh, arghh!). The 3 Onstar system buttons across the bottom of the mirror are rubber covers over membrane-type switches. The switches are actually part of the circuit board itself, but if you're VERY, VERY careful you can use an X-acto knife to cut the traces on the board from the trace ring land on the output side of the switch to the surface-mounted components. Then VERY, VERY carefully solder a small wire from the ring land to one of the unused pins on the back of the wiring connector for each switch (not the power switch, though - leave that one alone.) The input of the switches are all common to the main ground plane of the circuit board, so now when you press any of the switches you'll be sending a ground to whatever connector pin you soldered that switch's wire to. You can use this switched ground to activate the ground side of any relay, thus controlling nearly function on the car by touching one of the mirror-mounted buttons. They are momentary, though, so you'll need to wire in a latching circuit if you want that function to be constant on.
There are also led's under each button which are normally only on whenever that function of the Onstar system is activated - but they can be hardwired to the kepad's 5v supply and grounded from other unused pins on the wiring connector if you want by employing the same rewiring technique above. They could be wired so that they only come on when the vehicle' s dash lights are on so they're easy to find at night.
12 - keypad supply (5v) voltage (in) for the buttons
13 - ignition voltage (12v -main power IN to the mirror)
14 - Green LED signal (to the right of the Emergency button) - apply 12v to light LED.
15 - Red LED signal (to the right of the Emergency button) - apply 12v to light LED.
16 - return line to the LH outside mirror for day/night signal
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so, I think I'll use 4,6,7,8,12,13