Back inside the rear drivers side wheel well, near the bumper. There is a plug from the factory.
It does not have a towing hook.
Need to know what wires and which harness you speak of.
it is under the hood on the driver side in the fuse box
It does not have one.
A vehicle that is properly set up for towing. Meaning it has the towing capability for the trailer one intends on towing as well as electric brake and light hook-ups.
Easy way is to go to best buy get you a wiring harness that plugs into your factory harness.
Go to Radio Shack or Best Buy and get a wiring harness that plugs directly into the car harness.
It does not have one.
Have you looked under the vehicle? I'd be surprised if the wiring harness wasn't already there and taped up under the vehicle. Barring that, most business that sell and install trailer hitches will also install trailer wiring harnesses. If you're a DIY, go to the local auto parts store and ask. They probably have the wiring harness you need all setup to plug into the manufacturer's wiring harness.
You can find a wiring diagram that shows you how to hook up a trailer wiring harness on a 1998 Pontiac Transport at most auto parts stores. A Pontiac repair manual should have the diagram in it.
hook up the wires to the factory harness and listen you little heart out
You shouldn't need to bypass anything. You probably didnt hook up the remote turn on for the factory amp. If your using a harness, just hook up the blue and white wire from the harness of the radio to the blue wire coming from the factory wiring harness. If that doesnt fix the problem, one of your speakers is grounding out. Make sure all of your speaker connections arent exposed to anything. It should have nothing to do with your factory amo even if you have one.