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Are Extra Relays or Fuses Needed to Use Curt Trailer Wiring Harness on 2020 GMC Terrain


Im confused on this part and have emailed Curt and gotten no answer. Can I safely use Curt #56429 if my 2020 Terrain does NOT have the factory tow package? Their website here, https://www.curtmfg.com/part/56429, indicates it fits all models and mentions nothing about the factory tow package. This Curt harness has relays that come with it and install in the harness itself while the Tekonsha one comes with relays that go in the fuse box on the vehicle. My Terrain DOES have the trailer wiring harness tucked up behind the rear bumper. My rear fuse panel heres a great diagram of it: https://fuse-box.info/gmc/gmc-terrain-2018-fuses-and-relay, does NOT have the K1, K2, or K3 relays but it does have a 15 amp fuse in F13 and 10 amp fuses in F14 and F18. I assume those fuses are for the tail lights which are LEDs and would draw fairly little power so I would think those fuses would be sufficient to accommodate a small trailer assuming they also power that factory trailer wiring harness. This Curt wiring harness just seems much more appealing then the Tekonsha one which requires being wired directly to the battery. It also seems odd that GM would not install those K1, K2, K3 relays nor even run wires to them but still have that trailer wiring harness tucked up behind the rear bumper if its not functional. If I can safely get enough power through that factory wiring harness as is to power the lights on a small trailer lets a honest, a 1.5L cant handle much more Id be much happier than installing the Tekonsha one that requires being wired directly to the battery. Thanks in advance for any guidance.


Expert Reply:

I can understand how the wording could be confusing on whether or not the Curt # C94FR (56429) will work on your 2020 GMC Terrain, but I can confirm that it will indeed work for you without needing to install any extra fuses or relays on the vehicle.

The "with tow pacakge" selection on our site, refers to having the factory harness behind center of the rear bumper, like you mentioned having. According to my contact at Curt, this is present on all 2020 GMC Terrains, which is why they do not mention the need for a tow package.

The Curt T-Connector Vehicle Wiring Harness # C94FR includes the two relays that plug into this same harness, which is all you need to power your trailer lights. A direct battery lead is not required for this harness, like it is for the Tekonsha # 118764, which tees into your tail light connections instead.

I recommend using a mounting bracket like # 118149 to keep the 4-Pole secure to your hitch, for a nice, clean installation.

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Follow up Questions

Larry S.

Hell9 wiring for a 2919 equinox with connect under bumper cove4 on drivers side. Please verify the easiest harness. Thank you

Etrailer Expert
Reply from Chris R.

Since your Equinox is equipped with the factory tow package, the Tekonsha Wiring Harness # 118285 is the best option for an easy install. This will plug right into the bumper connection point you mentioned to provide you with a 4-Way connector to power the trailer's signal lights.

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