I have hardwired radar detectors before with no issues and spent over an hour trying to figure this out.

I have tapped into the pink and black wires leading to the sunroof control. Checking via voltmeter it seems to read the same output as when testing from the cigarette lighter.

Can't get the unit to come on. I have tested 2 detectors and a portable DVD player. Both come on via cigarette lighter but not the wires to the sunroof.

Any ideas or someone with similar experience?

 

Don't you want power only when ignition is on?
I am guessing you tapped into the sunroof wires upstream of the switch.
And the new detector does not have to be manually turned on every time via a momentary push-for-on button.
Just throwin some things out there.

 

If your rearview mirror has all the buttons, self-dimming, etc then there's power there. Invisicord makes a cable to do that and tells you what colors to tap at the back of the mirror.

 

I really am dumbfounded on this one since my connections seem to be solid and pulling power.

 

I made my own cord for ~$5 for my sports coupe. May make one for the Tahoe, and if I do I will post pics.

 

Really odd why I couldn't get it to pull from the sunroof power, but that's what it is. Hope it helps someone later.