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I just took delivery of a Boat and Trailer that requires a five prong harness for backup lights. I am curious to know if the new harness required for my truck (1999 Ford F250 superduty)is something I can go out and buy and install? Or do I need to bring it in to the dealership and have them wire it for me? Any help would be appreciated.
Mike_Jensen
03-08-2000, 03:04 PM
Wade
Chances are the fifth wire is a Red wire that is to be hooked up to your backup light circuit. This wire ties into a selinoid that cuts the pressure to your wheel cylinders, when you put your truck in reverse, to allow you to backup without slipping your brakes. These first stated to should up with the trailers that had disc brakes, now I am seeing them on drum brakes too.
If you can identify the brake light wires in the back of you truck they are not had to hook up.
Mike
Gone Again
03-08-2000, 08:27 PM
Wade-If your truck has the factory trailer plug at the rear bumper the circuit you need is wired to that point. With your ignition on and trans in reverse, probe each terminal with a test light till you find the one with power. Make sure this terminal has no power with trans in park/neutral. This is your back up light circuit and the one you need for your brake solenoid wire on your trailer-Tom
Wade, if you already have the towing package installed in the F250 you simply need to purchase the 7 pin(RV) to 5 pin(round) adapter. If you do not have the towing package you will then have to buy the wiring harness. This is inserted between two plugs at the rear of your truck. These wiring harnesses are oem affairs that are simple to install and come with instructions. Your parts man/woman will be able to show you the exploded view of your truck and show exactly where the harness is installed.
mlc