Parts Needed to Add a 4-Way and 7-Way Trailer Connector to a 2004 Freightliner Sprinter
Updated 10/30/2025 | Published 10/03/2025 >
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Question:
what harness kit for wiring a step van do i need to be able to connect my trailer? What model do I need for a Freightliner MT45 2004? this van does not have the harness to connect it
asked by: Gabe
Expert Reply:
Hey Gabe. Since you do not have the factory harness to add a 4-way or 7-way connector to your 2004 Freightliner Sprinter you will need the Curt Powered Tail Light Converter item # C59236. This connector is going to wire into your tail light harness and then you'll need to run a power line directly to your battery. This will give you a 4-way connector that controls your trailer's lighting functions.
If you're wanting to add a 7-way connector you will also need the Universal Installation Kit for Trailer Brake Controller item # ETBC7, you were looking at. This kit includes a pre-wired 7- and 4-way trailer connector that mounts easily at the rear of your vehicle with an included bracket. This kit is designed for use on a vehicle with an existing 4-way flat trailer connector and plugs directly into it. You have to install a 4-way connector to add a 7-way.
You will then connect the blue wire to the blue wire on the brake controller, connect the black wire to the positive post on your Sprinter's battery, the white wire to a suitable ground, and the yellow wire to the accessory circuit. This will provide you with the ability to control your trailer's brakes and also provide you with a 12v power wire for you trailer's battery.
What kind of trailer are you pulling and do you also need a brake controller? You can add this information and any other questions you have where it says Reply to Jerred H and I'll be happy to answer them.
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Jerred H.
10/30/2025
Hey Gabe, how did things go wiring the Curt converter and the ETBC7 kit on your Freightliner? Did the setup give you the trailer lighting and brake control you needed? Your update could make it easier for others working on similar step vans.