Basically, the original 16-pin connector has the parking wire on it, and only a park wire on it.
You pull out this 16-pin connector, plug in the autoharnesshouse 16-pin connector, and the original just dangles there since there's no 16-pin female connector on the harness.
You are right about the harness, the #3 pin is connects to the relay, which I guess is ground since they're using a black wire, but that bypass signal basically tells the HU that the parking brake is always on. When you're driving around it looks like this...
If the parking brake is "on", DRL's also will not turn on.
I tried splicing the original parking brake wire onto the #3 pin on the autoharnesshouse, and disconnecting it from the relay, but now all it does is turns "on" and "off", but DRL's still won't run...
Are you're DRL's working after using the harness? (When parking brake is "off", DRL's are running, when parking brake is "on", DRL's turn off).
Not really sure what to do here...