i just bought a 93' regal gs with the 3.8 and after going over the engine and finding various wires unplugged (washer motor & light) i cannot seem to find where this single red wire with a connector plugs into near the left (driver side) firewall. it comes out of the harness that has a few wires going to the remote positive terminal and the rest going elsewhere.. i have some pictures here:

http://www.myfilez.net/uploads/images/Picture_3.jpg

http://www.myfilez.net/uploads/images/Picture_4.jpg

I have the same wire in my car and it's not connected to anything. It's Probably only used for the 3.1 engine or something.

That wire is for the fuel pump test. Jump it with a hot wire to test operation of fuel pump when connecting fuel pressure gauge to schrader valve.

thanks