Troubleshooting Factory Trailer Wiring on 1998 Ford Ranger with Left Side Functions Inactive

Question:

Have a 1998 ford range, vehicle lights all working fine. Vehicle equipped with factory tow harness receptacle. When connected to trailer only right side works fine running brake turn and flasher and on left side only running lights. Trailers both checked out fine. Removed trailer connection from truck harness all 4 wires continuity checked good. Checked 4 wire harness on truck, one ground one power one signal one dead. Questions Any fix ? Ok to cap off harness and splice into tail and running lites? Appreciate any help thank you.

asked by: Robert C

Expert Reply:

You can try replacing the factory 4-pole harness on your 1998 Ranger with part # 118241 from Tow Ready. This has a round connector on one end to plug in to the OEM wiring under the vehicle on the driver's side. If the problem is downstream of that point, then this should fix you up. You can also check to make sure that any fuses labeled trailer or towing are okay.

If there is a problem in the wiring upstream of that connection point, then that may be tougher to find and correct. You can apply a tester like # PTW2993 to the contacts on the OEM connector under the frame rail (where the above part would plug in) to see if the signals are making it that far along.
If yes, then replacement harness # 118241 should take care of it.

If no, then you may be better off installing a new universal hardwire 4-pole harness at the taillights. This will bypass the truck's original trailer wiring and yes, you can simply cap off those OEM wires after you install a new 4-pole harness like # 119178KIT. An install video is linked for you.

expert reply by: Adam R