The problem ended up being an internal short in the trailer hitch wiring module. I removed it completely made sure that the insulation damages from the splicing were properly taped and that eliminated the short.
@ J.P Thank you for the heads up.
@ skyhawk Thank you for the schematics.
Hello every one, I have a 2006 Mazda5 Sport. My problem is can understand how brakes lights and signal lights are working normal,but the tail lights blows fuses right away when I replaced new fuses or new bulbs. How can I find wiring may get shorted to ground some where under the carpet. Could...