I just purchased a DDX8017 off ebay. Original owner said he never set the security code. I tried testing the unit by connecting the yellow and red power lines to the battery (+), and the ground and dvd safety wire to the ground(-). The unit powers up and reads, " Disconnected cadle found, please check wiring". Do I need to connect the speaker wire for a signal, or possible the antena? Need to make sure unit works properly before it is installed.

 

I would try Kenwood customer support. There number is on there web page.

 

Just curious, how much was it.

 

there could be several things affecting that. A few headunits use the antenna plug as a negative input as well.
Also last time i did a screen hookup i connected the saftey negative and it gave me the "screen disabled for your protection" message so i disconnected the negative and it worked fine.
couldnt hurt to connect a speaker to it either.