Adapting 9-Pin Trailer Connector to Work with 7-Way on Tow Vehicle

Question:

When connecting a 9-pin trailer to a 7-blade truck side I have two wires left over gray aux and orange reefer wire. Can I use a 4-pin flat plug to use with the two left over wires, by using an adaptor like 7-blade with 4-pin combo?

asked by: Roy

Expert Reply:

Are you speaking of an adapter like part # 37185? If so, I do not believe that would work well for you because the 4-pole connector on that adapter is not wired independently, rather it is tied into the 7-way.

To adapt your 9-pin trailer plug to work with the 7-way connector on the truck, you would need the 9-pin vehicle side connector that you referenced, part # R9CB. A length of 7-wire cable # DW04914-1 from the 9-pin would be tapped into the relevant circuits behind the 7-way, with the two remaining terminals being connected as needed. For a more temporary install, the 9-way R9CB could be temporarily attached to the truck, with a length of #127C500-1wired to the appropriate terminals on the rear of the connector. Wire the other end of the cable to a 7-way trailer end like # A7WCB, which would plug into the 7-way on the truck when needed. The remaining two terminals on the 9 pin would be connected as needed.

expert reply by: Mike L