Best Place for Running Wiring For a Trailer Brake Controller Into Cab on a 2022 Subaru Outback

Question:

2022 Outback Wilderness: Im looking for clarification on passing the wires thru the firewall. There is a big round grommet in the engine bay that looks easy enough to puncture. But on the inside it is not so clear. Would I need to cut a slit in the long black rubber tube on the inside? Would it be best to send my fish from the slot on the inside to see where it pokes through the engine grommet? Just making sure this is the best place to not damage anything. Thanks! My proposed cut location marked in Red on the photos

asked by: Todd S

Grommet In Engine Bay on 2022 Subaru Outback Wilderness
(click to enlarge)

Expert Reply:

I always recommend being careful when cutting into any grommets as you do not know what may be inside or behind them. I do see that in our Installation video for the Tekonsha P3 Trailer Brake Controller # 90195 they used the same hole to pass the wires through for. I have linked this video near the bottom of the page and you can see the location near the 13:00 mark of the video. There he only slits an opening in the grommet itself and not the rubber tube. As I see you are looking at the Redarc Liberty # RED24FR you will need the Pigtail # RED69FR. If you do not already have trailer wiring we have the 4-Way # C56040 and 7-Way # ETBC7 you would need.

expert reply by: Bud M

Todd S.

3/14/2024

Thanks Bud, Success! I got the wires thru the firewall. Can you help me confirm the cold brake sensor wire size and color (that attaches to the redarc controller)? The video on redarc page says brown wire. I do no have a brown wire. Other later model subaru owners are saying it is Yellow. It is also very small and hoping to confirm the size before installing the wrong quick connect. Thanks for your help!

Bud M.

3/15/2024

@ToddS It should be a brown wire on the brake light switch but you will always want to confirm this is the correct wire using a Test Light # PTW2993. The wire should get power any time the brake pedal is pressed and the power needs to cut out whenever the pedal is released.

Todd S.

3/14/2024

Hi Bud, More specifically can you find out if the photo on the inside of the car is the correct place (other side of engine wall) and that the wires would come through the rubber loom? Check out the videos for the RED24FR for the subarus, they mention cutting a slit on the inside of the car but never show it in the video, so I'm wondering if I have the right spot. Maybe I should send a fish from the engine side and see if I can see it trying to poke through on the inside? Thanks

Bud M.

3/14/2024

@ToddS I reached out with one of the installers and they did say that is a good place to run the wiring for the Brake Controller # RED24FR. I could not find an image of where it comes in on the cab but it is just above the throttle pedal on the right side.