I need to disable internal speaker when putting my MDA III into the car cradle. I don't want to use audio jack, so the purpose is to disable internal electronically on the system connector from where I take the audio signals to car stereo as well.

This link http://wiki.xda-developers.com/index.php?pagename=Connectors descibes MDA II - grounding the PIN19 (CAR ON) should do it - well, it does not actually, nothing happens no matter if I use 10k resistor or directly ground.

Since this is about MDA II, MDAIII might differ or has not the possibility at all.

Does anyone any experience with that?