How to Correct Malfunctioning Factory 4-Way Trailer Connector on 2005 Nissan Pathfinder

Question:

I have replaced the 4 way plug from the factory. But will not light my trailer. If i have another truck hooked up lights work fine. I also tried to clean the connections. Still the same results. You dont seem to have any answers for that. And I dont have a 12 point connector in the right front passenger side to hook up C56225. I was wondering if the harness for the 04 pathfinder 118361 would work? Was hoping for you to guide me in the right direction and help me with the part number i need to order to fix my problem. Thank you.

asked by: Brian H

Expert Reply:

Since you have tested your trailer with another truck you have eliminated the trailer as a source for the malfunction. The Curt harness you reference, part # C56225, includes two separate assemblies; one that attaches to the connector behind the passenger-side kick panel (and you note this connector is absent from your vehicle) and the other that connects underneath the vehicle at the frame rail. This second harness terminates with a vehicle-specific connector on one end and the standard 4-pole flat trailer connector on the other.

Tow Ready confirmed the other harness you reference, # 118361, will not work on the 2005 model year Pathfinder.

Since I am not sure at what point in the 4-pole wiring you inserted your replacement, you might try replacing the entire harness using part # 118263. This is the same as the harness supplied as part of # C56225. We also offer the similar Curt # C55441. Both of these parts (and others) for your Pathfinder can be seen on the provided link.

If you locate this connection point on the rear of the frame rail and disconnect the current 4-pole harness at the connector, you can test the OEM connector for proper signals without the rest of the 4-pole harness. You can use a tester like # PTW2993 to test each pin on the connector to verify that each carries the proper signal before purchasing a replacement 4-pole harness.

The four wires leading into the vehicle connector carry lighting functions as follows: Brown is for Running Lights; Yellow is for Left Turn; Green is for Right Turn (and the white wire is ground). Ground the tester and apply it one at a time to each pin while the corresponding lighting function is activated on the vehicle. (A helper will simplify this greatly.) When the Pathfinder right turn light is flashing you should detect an on-and-off blinking signal on the pin connected to the green wire. Repeat for the yellow wire with the left turn signal engaged, and for the running lights on the brown wire, which should deliver a steady non-blinking voltage when the headlights are on.

If these functions operate properly on the vehicle and if signals are present on the OEM connector pins, then you can replace the defective 4-pole harness with part # 118263 or # C55441.

If your testing of the vehicle connector reveals that the appropriate signals are not carried (but the lighting functions do operate properly on the Pathfinder) and the 4-pole used to work fine, then the problem lay upstream of the connector, and you may need to refer the problem to your local Nissan dealership. If it has not worked properly before now there may be tow package relays missing from the power distribution block. You might also take a look at the power distribution block to check whether there are any missing relays.