What 4 Flat Wiring will Work on My 2026 GMC Terrain?

Updated 12/30/2025 | Published 12/16/2025

Products Featured in This Question

T-One Vehicle Wiring Harness for Factory Tow Package - 4-Pole Flat Trailer Connector

(7)

$82.83

T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

(2)

$80.58

Question:

This product is listed as compatible with my 2026 Terrain, but it is not. The tow package connector on the vehicle is 4 pin, while the the harness is 6 pin. Same style connector just wrong size. Please advise on the timing of availability for a compatible wiring harness for the 2026 model Terrain. Also I would suggest you correct the website so no one else purchases this product for a 2026.

asked by: Bill

Expert Reply:

Hello Bill,

Thanks so much for reaching out about the harness. I just need a little more information from you if you don’t mind.

I see that the T-One Vehicle Wiring Harness for Factory Tow Package # TK67KR is the correct replacement if your Terrain has the factory tow package. Did your 2026 GMC Terrain come equipped with that package? I attached an image that shows where it specifies “with Factory Tow Package.”

If it did not come with the tow package, then you would actually need the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # TK68DR. This one installs by plugging in behind the tail lights, and it does require running a power wire up to the battery.

I really appreciate your time, and I look forward to hearing back from you so I can get the right wiring set up or removed if needed.

expert reply by: Kate F

with Factory Tow Package
(click to enlarge)

Bill

12/30/2025

As I noted in the original comment, the connector on the vehicle tow package is 4 pin, while this wiring harness is 6 pin. It is not compatible. I can send you a picture of the plug if that helps. I believe GM changed the connector plug size for the 2026 model.

Kate F.

12/30/2025

@Bill Sorry to hear that Bill. Yes, can you please respond directly to the email that you receive with pictures of the connector on your truck so I can get this resolved. This may have been a fit that changed this year, I really appreciate you taking the time to do this. After I receive the pictures I will be able to get a return label sent over to you as well.