How to Add a 7-Way and Brake Controller to a 2008 Ford E-450

Updated 01/15/2026 | Published 01/10/2026

Products Featured in This Question

Tekonsha Primus IQ Trailer Brake Controller w/ Custom Harness - Up to 3 Axles - Proportional

(2164)

$108.84

Hopkins Engager Trailer Breakaway Kit w/ Charger, LED Tester, Hardware, and 5 Ah Battery - Top Load

(753)

$72.04

etrailer Electric Trailer Brakes - Self-Adjusting - 10" - Left/Right Hand Assemblies - 3.5K

(3054)

$160.28

Easy Grease Trailer Hub and Drum Assembly for 3.5K Axles - 10" - 5 on 4-1/2 - Pre-Greased

(1732)

$99.04

Universal Installation Kit for Trailer Brake Controller - 7-Way RV and 4-Way Flat - 10 Gauge Wires

(3412)

$118.05

Question:

I have a 2008 E-450 RV. I am trying to find out if this unit has wiring to the rear for electric trailer brakes. It does have trailer lights. The wires are not there for brakes. There are some connectors in the rear wire harness that are unused. I am not able to find an unused connector under the dash that maybe was for a brake controller.

asked by: Sparky B

Expert Reply:

Hey Sparky. If your 2008 Ford E-450 came with a factory 4-way connector, the factory brake controller harness is a brown 6 pin connector located behind the hood release latch up near the firewall inside the cab. There is a gray connector in a similar location that maintains the same pigtail connector however, you are looking for the brown pigtail connector.

For a brake controller, and custom wiring adapter, I recommend the Tekonsha Primus IQ Trailer Brake Controller w/ Custom Harness item # TK38ER. This is one our most reliable and popular brake controllers. It's a proportional controller with the settings easily accessible.

Since your E-450 only has a 4-way connector, you'll also need the Universal Installation Kit for Trailer Brake Controller item # ETBC7. This will provide you with the required 7-way connector that your 4-way will plug directly into. You'll run the blue brake wire and power wire up to the front of your motorhome. The blue wire will connect to the back of the factory harness and the power wire will go to the battery.

What kind of trailer are you pulling? Looks like you're swapping out brakes.

You can add this information, along with any other questions you have, where it says Reply to Jerred H.

expert reply by: Jerred H

ETBC7 Wiring Diagram
(click to enlarge)

Sparky B.

1/12/2026

Yep I found the brown connector under the dash. It was right there this time when I looked. Red, blue, black and a green wire. I also have the same color wires at a connector at the rear. This connector is round with 4-pins. Do you have an adapter for this connector? Vehicle already has the RV 7-prong at the rear so I don’t need that. I’m adding electric brakes to a 6x12 enclosed single axle trailer that I pull behind RVs. I travel in the mountains a bit and would like more braking. And then I will have it if I pull something heavier that has electric brakes. Thanks!

Jerred H.

1/15/2026

@SparkyB That's great you found it! The wires that go into that brown 6 pin connector should be connected to a ground, power source, brake signal, and the blue wire to the 7-way connector. Are you saying the factory brake controller adapter isn't connected to anything? I completely agree on why you're adding a brake controller. I would definitely want trailer brakes traveling through the mountains as well.

Sparky

1/15/2026

What I am looking for is harness that can plug into the round 4-pin connector located in the left frame rail at the rear of the vehicle. 2008 E-450. This harness would allow me to get the brake control wire and hot lead to trailer plug in. Do you folks have this harness?

Sparky

1/15/2026

I’m sorry, I believe the 6pin brown connector is connected the 4-pin connector in the frame rail. Red and Blue wires are same gauge. I don’t what the blac and the black/green are for.