Can You Use 4-way To 5-way Adapter Without Connecting Blue Wire To Vehicle?

Question:

Trailer has a 5way connection Reverse lights only - no surge brakes and it is loaded out to family/friends at times. Those family and friends have 4way connectors and there is no need for them to buy and install a permanent conversation/adaptor. Im looking at the 4way to 5way adaptor C57187. Can either of these be used in reverse without causing shorting, ground issues or other problems if the extra blue wire is cut off or terminating the end? If I used a 4way to 4way extension and similarly the blue wire connection will be left exposed on the trailer side - any concerns for issues arising while in use or long term? Last, Ive been told to just plug the trailer 5way into the vehicle 4way leaving the last terminal off of the plug similar related concerns mentioned above - on my families truck the OEM adaptor housing is not wide enough to do so. Thanks in advance for your guidance!!

asked by: William R

Expert Reply:

You can use an adapter like the Curt Trailer Connector Adapter - 4-Way Flat to 5-Way Flat - Vehicle End # C57187 and just cut the blue wire off the adapter since you are not needing to use the reverse lights. This will not be in reverse, as the adapter is designed to convert a 4-way vehicle connector to a 5-way trailer connector exactly like you are wanting to do

This will protect the 5th pin of the 5-way connector from debris and corrosion over time and will not cause any shorts or wiring issues as the power comes from the vehicle side and not the trailer side.

Another option is as you mentioned, you can just plug a 4-way connector directly into a 5-way trailer connector but it will leave to 5th pin exposed. If you choose to go this route adding dielectric grease # 11755 will help to prevent corrosion on that pin.

I included a video of the # C57187 for you to take a look at.

expert reply by: Samuel C