Installing a Brake Controller in a 2009 GMC Sierra 1500
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Question:
I have a 2009 GMC Sierra 1500 with factory tow package. I am installing a trailer break controller, so from under the dash on the drivers side I pulled the wires down from the left side of the steering column and they are tagged...the bundle has A 12 gauge red wire with a black stripe, A 12 gauge dark blue wire, a 14 gauge yellow wire, a 14 gauge lime green wire with a yellow stripe and an orange 14 gauge wire. The tag on this group of wires says white wire is ground, dk blue wire aux, red/ black wire batt, and light blue /wht chmsl, org chmsl . I connected the two red positive wires under the hood to the two power post that are on the front of the fuse box, both red wires were wrapped on the lower sides of the fuse box on the driver side over the fender well. I installed a 40 amp breaker that is in line with the smaller red wire and post. With a multimeter and truck running and no trailer connected, the yellow wire doesn’t have voltage or ohms, the red/blk wire has 14+volts, the lime green/w yellow stripe has 13.8 volts, after pressing the brake pedal it has 14+ volts, the dark blue doesnt have volts or ohms. After connecting the Hopkins Agility Electronic Break Control, dk blue to dk blue, yellow to white, light green/yellow stripe to red and red/Black stripe to black. There is still no trailer attached or connected. The Hopkins controller has a blank controller screen. Are these volt / ohms readings and wires installed correctly? In the instructions the Agility will indicate a blank screen till trailer is connected.
asked by: Dan
Expert Reply:
It does look like you might have made some wiring errors during the installation. I have also linked a video that will help. On the 2009 GMC Sierra 1500 when installing a brake controller make the following connections to the brake controller:
Truck red wire to controller black wire (12 volt power to brake controller)
Truck dark blue to controller blue wire (output to trailer brakes)
Truck light blue (or orange if light blue doesn't work) to controller red wire (input from brake switch)
Truck white wire to brake controller white wire (ground)
Under the hood the ring terminal for brake controller power is located directly to the right of the power distribution box. It is taped to a wire harness between the driver-side front fender and the power distribution box. Cut the tape to release it from the harness. Then run the wire to the front of the power distribution box and hook the ring on the left post (M6 stud).
The ring terminal for the 12-volt power lead for the 7-way trailer connector (not the brake controller) is located to the left of the power distribution box. It is taped to a wire harness under the power brake booster. Cut the tape to release it from the harness. Then run the wire to the front of the power distribution box and hook the ring on the right post (M8 stud).
Tighten the ring terminals onto the posts using nuts (M6 # 185916 and M8 # 185917 nuts available separately). Then activate the brake controller power post by inserting an automotive style 30-amp fuse into the correct slot in the power distribution box.
Activate the 12-volt power lead post by inserting an automotive style 40-amp fuse into the correct slot in the power distribution box.
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on Wiring
Donnie
3/19/2025
I can not find the red wire that is supposed to be between my fuse box & the drivers side fender. There are wires taped up with conduit going into the side of the fuse box. I’m looking for the wire that supposedly reads aftermarket brake controller power. I’ve seen pics with the same fuse panel as I have but on those as well, I see no red wire with the terminal in it. All help is greatly appreciated