why did you replace the wiring in the first place?
they make a device that plugs into your vehicles connector to test the leads to it. harbor freight sells one also.4$http://www.harborfreight.com/four-way-trailer-light-tester-66526.html
did your dad check that end of the wiring?
Factory wiring could be an issue but its also cheap to add a 4 plug trailer harness off the rear brakes too. The converter on my truck that goes from factory to female 4 plug has the test right on it. I think it was 20 bucks....If you have a trolling battery lying around use it to test your wiring job indepemdant of your vehicle if you want to be sure its not your fault!
get a set of leads from harbor freight and run a separate ground wire then you will have the hitch, the lights and the separate ground cant beat 3 ground sources thats most always the trouble
I know you already said you are getting it done to save grief and I get that, but... maybe for other's benefit here are my experiences.It is best to buy a kit designed specifically for the vehicle it is installed on. Generic ones can do exactly what you are experiencing.Water is the enemy, but unavoidable as you will be submerging the trailer launch. Bulbs will get wet & blow no matter how good the gaskets around them or how much grease you put around them. Switch to LED bulbs if possible and this is solved.You should to test trailer lights every time you take it out for safety. If you do find something is out a good tool to trace problems is a continuity tester. Basically you just stab the pointy end into any positive or 'hot' wire and then ground the alligator clip. If wire has power the little bulb on tester will light. Often times it is a bad ground as someone pointed out.Make yourself a little kit box with tester, extra bulbs, fuses, sand paper to fix ground points etc, and you will be a pro in no time.Here is an example of a tester from Lowes:http://www.lowes.com/pd/KD-Tools-Multimeter-Meter/4740304?cm_mmc=SCE_PLA_ONLY-_-FashionFixtures-_-SosAtg-CeilingFansOutdoorLi-_-4740304:KD_Tools&CAWELAID=&kpid=4740304&CAGPSPN=pla&k_clickID=354951af-90b9-4ca8-b303-98d343b02e89Harbor Freight probably has decent inexpensive ones too.One word of caution, you will quickly become proficient at this and your friends or folks at the boat launch will expect you to fix theirs.
Guys I'm just going to have the garage fix it. Time is money for me as I'm self employed. I'd rather have them pull their hair out and spend more time in my shop making money. I wasted a whole day on it already.