Parts Needed for Inherited 2010 Sierra to Tow Trailer with 7-Way Connector

Question:

I literally inherited my pickup. It is a 2010 GMC Sierra and has a ball for towing. Likewise it also has a switch in the cab that lights up a trailer icon on the dash....I assume this is for trailer brakes. It only has a 4 pin flat connector on the truck, my 18 foot trailer has a round 7, what do I need to make everything work?

asked by: DANNY P

Expert Reply:

We have everything you need to set your 2010 GMC Sierra up for towing your trailer that is equipped with a 7-Way connector and electric brakes.

To start you will need to install a fully functional 7-Way connector. There should be a bundle of factory wires above the spare tire of your Sierra. These wires can be used to install a 7-Way harness like the Pollak # PK11898. You will just need to connect the wiring from the 7-Way pigtail to the wiring on the truck, making sure to match them for function. I recommend using a circuit tester like # PTW2992 to test the factory wires under the spare tire while you have a buddy go through the lighting functions in the cab. On the Pollak harness red is for left turn/stop, blue is for brake output, green is for right turn/stop, black is for 12V power, brown is for running lights, yellow is for backup lamps, and white is for ground.

Then with the 7-Way installed you just need to add a trailer brake controller to the truck so that you can activate the brakes on the trailer. The switch that you described is likely for the truck's towing mode and not a factory brake controller so one will still be needed. For this I highly recommend the Tekonsha Prodigy P2 # 90885. This is an excellent proportional controller that will activate the trailer brakes at the same time and with the same intensity that you apply to them in your truck.

There isn't a factory plug under the dash for a plug-and-play installation of the controller, but all the needed wiring should already be run. You will connect the brake controller wiring to the wiring already present under the dash. On the brake controller the blue wire is for brake output to the 7-Way, the red wire is for the cold side of the brake light switch on the truck (the wire above the brake pedal that ONLY gets power with the brake pedal depressed), the black wire is for 12V power, and the white power is for ground. You will again want to use a circuit tester to verify the functions of the factory wires to ensure you make the correct connections. I have attached an installation video to assist.

Please let me know if you have any further questions and I will be happy to help!