7-Way Adapter vs. Full 7-Way Wiring Kit for 2005 Jeep TJ with 4-Pole Wiring

Question:

HM40975-11933 was purchased for my Jeep based on the custom fit but what part is needed to install? I believe the 4 way but I confused myself. Thank you

asked by: Brice H

Expert Reply:

Pollak part # HM40975-11933 is a kit that includes a short OEM - to - U.S. Car Connector wiring harness and a 7-way/4-pole combination connector that mates with the round U.S. Car connector end of that harness. The other end of the harness mates with the rectangular OEM connector under the vehicle which will be present only if your Jeep TJ came from the factory with a 7-way.

If your Jeep has a 4-pole wiring harness like # 18252, with a connector like the one shown in the linked photo, then this can be converted to the 7-way type connector using part # 37185. Your 4-pole harness simply plugs in to the mating connector on this part. The basic lighting signals from the 4-pole are then reassigned to the appropriate pins in the 7-way connector format.

The linked article will show you which signals are carried on which pins in a 7-way as well as in the other common wiring formats.

Using the adapter # 37185 does not by itself provide additional circuit connections for brakes, 12V power and reverse lights, but it DOES allow the 4-pole lighting signals to be conveyed in the 7-way connector format. If you have 4-pole wiring you wish to convert to a fully-functional 7-way (WITH the additional circuits for trailer brakes, 12V power and reverse lights) then instead of # 37185 use kit # ETBC7 which includes part # 37185 along with the wiring and other items needed to have a 7-way wiring setup.