What Is The Blue Wire For On A Typical 7-Way?

Updated 07/07/2025 | Published 06/29/2025

Products Featured in This Question

Pollak Replacement 7-Pole, RV-Style Trailer Connector Socket - Vehicle End

(745)

$16.70

Hook Probe Circuit Tester

(66)

$13.25

Question:

I’m using the curt 58151 7 way rv blade connector. My truck is an 07 ram 2500, all the charts I see talk about a blue wire that I don’t have. As you can see I have 2 grounds and 2 greens, the red wire is hot. Any help is greatly appreciated. Thanks

asked by: Benjamin

Expert Reply:

Hello Benjamin, thanks for reaching out. The blue wire on a standard 7-way is for brake controller output. Wire color is not always universal though. I have included a picture showing the typical 7-way color coding. If you are unsure of which wires are which on the vehicle side you would need to use a wire tester like part # PTW2993 to poke around and determine the wire functions.

Did your truck come from the factory with a 7-way? Or are you adding one aftermarket?

expert reply by: Jesse M