Nuts.

Okay, quick RS232 lesson. Data Terminal Ready is a signal that the terminal (in this case, the computer or the empeg) sends to the Set (in this case, the GPS) that it's ready to receive data. Your GPS isn't seeing it turned on, so it's not sending anything. Surprising, really, that it would do that. Most such things send regardless.

Tying it to Carrier Detect is a common cheat, as it's basically always on. Except in your case. And you have no other signals always on. You'll probably have to cheat it in there somehow.

When you attach it to your computer, you use a straight-through, right? If so, you should be able to use the same cable with the empeg. (Someone correct me if I'm thinking backwards, but since we use a null-modem to connect the computer and the empeg, then the empeg is a Terminal just like the computer, right?) And the empeg ought to set DTR.

Weird. I'm confused.