Just curious, if you could buy a compact, pre-fabbed circuit that would enable your climate control head to dim like it did with the factory radio, what would you be willing pay (shipped) for that? $50? $40? $20?

I have a Pioneer double DIN DVD that dims with my lights. All I did was hookup the dimmer wire... ?

Joel's talking about dimming of the HVAC display. When you add an aftermarket head unit, you lose the ability for the HVAC to dim with the gauge lights. It stays on max brightness all the time.

Joel, it's not just aftermarket head units. If you swap a later Chevy 1.5 DIN CD into the 91-93s, you lose the dim as well (speaking from experience...)

Aaah. I was not aware of that.

Jason is correct - the stock radio sends some sort of signal to the CC unit.

Purple wire, if memory still works after all these miles