Gentex 261 Auto-Dim Problems

Hello, I picked up a Gentex 261 mirror to install in my vehicle. It has auto-dim, OnStar, compass, & temp. I've actually built a test bench with a 16 pin connector to test gentex mirrors. However, I've never encountered a 261. When I power the ignition it comes on normally, the compass and temp display properly, but the autodim does not function with the sensor covered. I'd read that pin 5 is for the ambient light sensor to trigger the autodim so I tried powering it, nothing. Then I left pin 5 powered and switched off the ignition and the mirror dimmed. But it would not dim with ignition on. What am I doing wrong? How can I make the autodim work with the ignition on?

Probably the pin you are using for ignition is actually the reverse lamp wire that prevents dimming in reverse and pin 5 is actually ignition. Just a guess.

I appreciate the suggestion, however pin 5 is not ignition because when pin 5 is switched on and pin 13 (ignition) is off there is no compass or temp display. Also, the reverse wire is on pin 9 (which I have on a 2 position switch which can be grounded or have +12V). But, again I appreciate the suggestion. This honestly has me stumped. I tested a Gentex 511 on the very same test bench I'm using for this 261 and it worked flawlessly, and the 511 is now serving me well in my other car (a Fiero).