Parts Needed to Install Brake Controller on 2021 Subaru Forester
Updated 02/03/2026 | Published 07/27/2024
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Question:
Hello, I plan to tow an open trailer and ATV on my 2021 Forester. Estimated weight between the two will be 1300-1400 LBS. With this in mind, Ive also looked into installing trailer brakes uninstalled on the trailer I plan to purchase. Im unsure whether the Subaru wiring harness supports a 7 pin configuration from the factory. Will I need to utilize a 4 to 7 pin adapter to connect to the trailer? Will the braking system need to be operated by its own battery?
asked by: Timothy D
Expert Reply:
Hey Timothy, so your 2021 Subaru Forester is not pre-wired for a brake controller but you can hardwire one like the P2 part # 90885 in. You'll need to start with a 4-way like the part # 118467 if you don't have one already and then for a kit to convert it to a 7-way and wire in the brake controller you would need the part # ETBC7 and you'd have everything you'd need.
The brakes of the trailer will draw power from the Forester's battery and would not require a trailer battery be installed.
Product Page this Question was Asked From
Curt T-Connector Vehicle Wiring Harness for Factory Tow Package - 7-Way Trailer Connector
- Custom Fit Vehicle Wiring
- Trailer Hitch Wiring
- Vehicle End Connector
- Converter
- Factory Tow Package
- 7 Round
- Plug and Lead
- Plug-In
- Visible
- CURT
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Jameson C.
2/3/2026
Hey Timothy, how did things go wiring the brake controller and 7-way setup on your Forester? Did the ETBC7 kit give you everything you needed to get the trailer brakes working smoothly? Your update could make it easier for the next person setting up a similar tow rig.