Converting a 7-Way Round Pin Trailer Connector with a 7-Way Blade Connector on a 1992 Ford F-250

Question:

I have a 92 F250 that has a 7 pin round wiring harness and my trailer has a 7 pin flat harness. How do I change out this adapter to make it work with the trailer? The wires dont appear to be the same colors as noted on many of the diagrams I have found on the two types of 7 pin adapters.

asked by: Kirk T

Expert Reply:

In order to install a 7-Way blade style trailer connector on your 1992 Ford F-250, you will first need to test the wires by function on your existing 7-Way Round connector using a circuit tester like # PTW2993. The wire colors not matching is a common problem which is why it is necessary to test the wires themselves for function in order to pin the Pollak Black Plastic, 7-Pole, RV-Style Trailer Socket - Vehicle End, # PK12-707E, correctly.

Using the circuit tester, find the wire that provides constant 12-volt power. This wire will attach to the 11 o'clock position on the back of the 7-Way blade connector.

Next, find the wire that has 12-volt power when the vehicle headlights are on. This wire attaches at the 1 o'clock position on the back of the 7-Way.

Turn on the trucks left turn signal and find the wire that carries a signal in unison with the blinker. Attach this wire to the 3 o'clock position on the back of the 7-Way.

Next, find the wire that carries a signal when the manual override lever is engaged on the brake controller. Attach this wire to the 7 o'clock position on the back of the 7-Way.

Then, turn on the trucks right blinker. Find the wire that carries a signal in unison with the right blinker. Attach this wire to the 9 o'clock position on the back of the 7-Way.

The center pin on the 7-Way blade is for reverse lights. This may or may not be hooked up on your current 7-Way round. If it is not, route a wire from the 7-Way blade to a reverse light wire.

The remaining wire will be the ground. It attaches to the 5 o'clock position on the back of the 7-Way. I have included a link to trailer wiring information that includes the functions for both a 7-Way Round and 7-Way Blade style connector that should help in replacing your trailer connector.