Trailer wiring '00 Grand Marquis
 

I am installing a new hitch and wiring. Is it ok to hardwire a 4-pin connector that i have laying around my garage, or do I need to buy some special wiring kit to do the job right. I don't know about the effects it may have on the vehicles electronics? or circuitry? I have seen some wiring kits for sale that have modulator circuit built in, don't know what thats for or if it's necessary. Anyone who has expert knowledge in this area please help.

No, you should be fine hardwiring it.

Ground to the frame, running lights to the running light circuit and wire left and right brakelights.

that's pretty much the way my 93 crown vic is wired. needs a new receiver though if I ever decide to use it. Just a long set of wires into the trunk that get flopped over the weather stripping to hook up to a trailer. now if you're looking at making one that mounted to the hitch instead, you may have more interesting time running the wires out to the hitch since they're all inside the car.