Question Was Asked By - David

What wires on the Adapter 4 Pole to 7-Way and 4 Pole are Used for What Functions

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Trailer Wiring Diagrams

Question:

I assume the blue wire is for the trailer brake. What is the black wire used for and the yellow wire used for?

asked by: David

Expert Reply:

You are right the blue wire is usually for electric trailer brakes and runs to the blue wire on the brake controller. In some cases the blue wire is wired to the backup light circuit to disengage hydraulic surge brakes when backing. The black wire is normally used for accessory power and the yellow wire is auxiliary power that is used to charge the battery.

expert reply by: Bob G

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