So I decided to upgrade the ancient nav system using the trick of removing the display from the original, flip-up clamshell and gluing a Garmin DriveSmart 66 into the resulting hole. It’s a major upgrade and I’m mostly thrilled with the result. There’s one nagging issue, however. In the course of this upgrade (plus a Bluetooth upgrade), I unplugged the old nav DVD player and also removed it from the MOST loop. Why have this thing sucking up power while doing nothing, I thought? Also, when I put the display clamshell back in I didn’t bother to connect the signal cable from the DVD player. I only reconnected the power plug that fed the clamshell itself. When I re-installed the clamshell it was open. The first time I powered up the car, the clamshell motors lowered it into the closed position. Pressing the Nav button (or anything else) on the center panel didn’t raise it. I opened it manually and waited for the motors to finish cycling. The clamshell stayed open and pressing the Nav button wouldn’t close it. It remained open when I turned the car off. The next time I started the car, however, the motors engaged without any input from me and closed the clamshell. Again, pressing panel buttons had no effect.
I’m wondering if any other adventurous soul has experienced anything like this and whether there’s a fix?

 

The opening of the nav display is controlled by the MMM that you bypassed. You'll either need to reconnect it or build an electronics circuit to send data to the screen on the serial line of the video cable.

 

Well #%*@, wouldn’t you know it? I took the factory nav out of the MOST loop because the Bluetooth mfg suggested it would make their device more stable (it doesn’t ) Sigh, I’m becoming an expert on disassembling interior trim pieces. 😕 Thanks so much for the quick and knowledgeable response.

 

Just following up to say that I re-connected the nav unit and the clamshell now opens and closes.