Has anyone had this problem?
I have a utility trailer with newly wired trailer lights. When I plug it into my factory 4 prong plug, only the passenger side works. I tried the same trailer on my neighbors GMC Envoy, and it works just fine. I brought my Tacoma to the dealer to have them check it out. I know the parts manager there, and trust him. He said that the mechanics checked it out and said that everything works fine. He said that Toyotas are wired differently and require a "Negative Ground." What does this mean? Any suggestions?
Also, I have a tailgate light bar that plugs into the 4 prong plug and it works fine.