Using a 7-Way to 5-Flat Trailer Adapter # HM47675 for Trailer with Electric Brakes

Updated 09/12/2014 | Published 09/10/2014

Products Featured in This Question

Hopkins Multi-Tow Trailer Connector Adapter - 7-Way to 5-Wire Flat/4-Wire Flat and 12-V Power Socket

(118)

$22.35

40 Ft 5-Way Trailer Wiring Harness - Wishbone Style - 30" Ground - 5' Auxiliary Wire

(175)

$37.80

7-Way Molded Trailer Wire Connector - 3' Long

(195)

$32.81

Question:

Im looking at your 7 way to 5 flat adapters. It appears looking at the picture of the 7 way, that the brake contact is missing on all the various models. How do they work the brakes, if the contact is missing. Am I reading the diagrams wrong? Thanks.

asked by: David F

Expert Reply:

The 5th wire on a 5-pole flat trailer connector like the harness # A40W5B can be used for either a reverse lockout function (as on a surge brake coupler) or to deliver a signal for electric brakes. It just depends on how your trailer is wired.

7- to 5-pole adapters like the Hopkins # HM47675 will typically take the 7-way's center pin function and assign that to the 5th pole on the 5-pole output. For an RV-style 7-way this center pin usually carries the reverse light signal, not a brake controller output signal.

You can simply wire a 7-pole trailer plug such as Hopkins # H20042 (3-foot) to your trailer wiring BY FUNCTION using butt connectors. Simply cut off the trailer's 5-pole and wire in the 7-way plug. This will avoid the need for adapters.

A linked article on wiring may be helpful to you.

expert reply by: Adam R