Where Do the Trailer Wiring Harness Relays Install on a 2018 GMC Terrain

Updated 02/19/2018 | Published 02/18/2018

Question:

It came with zipntoes and then two relays? not sure where or what the relays or fuses looking things go or what there for?

asked by: Chris

Expert Reply:

For wiring harness # C94FR you may not need the relays if they are already present on your 2018 GMC Terrain. If the wiring harness works, then you can just hold on to them as spares. If it is not working, then they will need to be installed.

Locate the fuse panel at the back of your Terrain. It is behind a little access plate on the driver's side. There are 3 relays for tow package wiring in this box. K1, K2, and K3. The relays will need to go in the K1 and K3 locations. The K2 spot is for trailer reverse lights but that function is not present on a 4-Way flat trailer connector so there is nothing you have to do with the K2 spot.

expert reply by: Michael H