Correct Wiring Harness for the Curt Triflex Brake Controller

Question

Question:

I was looking at a Curt Triflex brake controller, but I am having trouble verifying the correct wiring harness to install it into a 2008 GMC Denali XL. My initial finding is the C51342, but I am not sure. Can you help?

asked by: TJ R

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Expert Reply:

The Curt Triflex brake controller # C24VV is an excellent choice when adding a brake controller to your vehicle. This brake controller activates trailer brakes in proportion to your vehicle's braking action, automatically adjusts trailer's braking based on deceleration of tow vehicle, and activates immediately with no pausing like with time-delayed brake controllers.

But when trying to find the correct wiring harness to install it into a 2008 GMC Denali XL, the answer is the Universal Wiring Adapter for Curt Trailer Brake Controllers Item # C51515. This wiring adapter is designed for vehicles that do not come equipped with a factory brake control wiring harness port. This 2008 GMC Denali XL is one of the vehicles that have all the wires run but there is no connecter to plug the adapter in. One end plugs into your Curt trailer brake controller while the other end splices into your vehicle's wiring. The Deka Heat Shrink Butt Connectors # DW05745-5 will be what u need to get the job done.

The wiring harness in the vehicle is located under the dash between the ebrake and brake pedal. Look for a bundle of wires with a white tag hanging off it. Wires connect as follows:

Red vehicle wire to black brake controller harness wire
White vehicle wire to white brake controller harness wire
Light blue/white striped wire on vehicle to red brake control harness wire
Dark blue vehicle wire to blue brake control harness wire
Orange wire on vehicle isn't often used.

In order to make your brake controller # C24VV and the Wiring Adapter # C51515 work, you will
need a Custom Multi-Tow 7-Way and 4-Way Trailer Connectors # 30955. This will allow you to have a 7-way connection at the back of your vehicle to connect to your trailer.

Attached are videos of the brake controller and wiring harness installations.

expert reply by: Timothy G

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Answer 1

Great question. As a general rule, when your trailer is loaded to it's full capacity, there should be a minimum clearance of 3 inches between the top of your tire and the underside of your fender.This should give you adequate clearance for…

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Answer 2

In order to determine the torque rating for the lug nuts on your trailer you will need to know check out the chart I attached that shows all of the torque specs for all the trailer lugs available based on stud size, wheel material and wheel size.

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Answer 3

Good morning, Cliff. As of today (3/27/24) we are expecting the #KE33JR tire/wheel combo to be in stock in about 2 weeks. Hopefully this means we can take our own pictures and put them on the site within maybe about 3-4 weeks from now. What I can…

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Answer 4

A 4-Way trailer connector has the basic lighting functions only; running lights, left turn signal and brake lights, right turn signal and brake lights, and ground. A 7-Way has these functions and a 12 volt circuit, a circuit for electric trailer…

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Answer 5

If you just need a 4-pin to 7-pin trailer wiring adapter, then you can use part #C57672. This will plug into the 4-pin trailer connector on your brother's vehicle and give him the 7-pin socket for the trailer. Keep in mind, this will only give…

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Answer 6

When wiring a trailer connector, it is best to wire by function, as wire colors can vary. We have an excellent wiring diagram on our website, I will provide you a link so you can look at it. If you are looking at the inside of the trailer connector…

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Answer 7

You have it right so far, the 4-way connector is just as you have stated. Remember that Yellow has a L in it so that is the left side brake/turn signal and green has a R in it so that is the right side brake/turn signal. The colors for wiring a 7-way…

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Answer 8

It could be a tow package fuse on the vehicle. Use the owners manual to find the locations of fuses/relays related to the tow package wiring to check them and replace as needed. If the issue is not a fuse or relay then you can test the vehicle side…

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Answer 9

The only difference between 7-Way Utility and 7-Way RV is the color of the wires. The pin outs are the exact same so either would work just fine with the other. If you check out the picture I attached you'll see that the functions are all the…

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Answer 10

Since wire color codes are NOT universal, we always recommend wiring by function, rather than wire color. If you look at the Trailer Wiring FAQ article I have linked you to, you can see some diagrams showing the proper way to wire a vehicle and…

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Answer 11

It's a wire color difference but not a function difference on the pins of the 7-way. The difference comes from the fact that the two different styles are representative of two different areas that uses trailers. Traditional is usually seen on…

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Answer 12

On a 7 pin round which is the common connection on a semi trailer, the clearance/marker lights are at the 10 o clock position when you look at the trailer wiring connection. When looking at the connector on the back of the truck, that will put the…

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