Truck cap 3rd brake harness

brhodea · Sep 7, 2024

With help from Dave at FBC, I was able to wire up the 3rd brake light of my Leer cap on my 2024 Tundra. Apparently, the 4th gen Tacoma & 3rd Gen Tundra share some wiringissues that make the wiring not as easy as it was on my 3rd gen Tacoma.
Since the brake light on both the Tundra and Tacoma are wired similarly, here's how I installed installed the FBC harness as to not tap the aluminum brake/blinker wire.

Cab side 3rd brake harness to power cap 3rd brake light/dome light, link.
https://fbchs.square.site/product/t...-harness/49?cp=true&sa=false&sbp=false&q=true
The harness is OEM quality, I highly recommend this route to wiring the cap 3rd brake light.

1. Tools, not pictured a T27 torxs driver to remove the headliner visors. The only 2 sockets needed are a 10 & 14 mm

I've pictured the steps from the driver's side, all steps need to be repeated on the passenger side to pull down the headliner down to access the cab 3rd brakelight harness for the plug and play power to the cap 3rd brake light/dome light.
I started on the driver's side removing A-pillar grab handle. Pop the bolt covers with a trim tool and remove the 2 - 10 mm bolts.

Remove the 2 screws on the driver's side headliner sun visor using the T27 torxs driver.

Next, remove the rear driver's side grab handle using a trim removel tool and a 10mm to remove the 2 bolts.

Next, remove the hanger hook using a small flathead screwdriver to pry the cover off. Then with needle nose pliers, metal spring clip together and remove.

Next, remove the drivers, lower seatbelt anchor. Pull straight towards the passenger side by the top of the bolt cover, then with the 14mm socket, remove the bolt.

Remove both front and rear door seal step trim, by gently pulling up fromeither the front or rear of the trim piece.

Remove the lower D-pillar trim piece. There are 2 clips at the top of this piece connecting it to the upper trim piece. Gently pull to separate.

On the bottom of the upper D-pillar trim, remove the 2 push trim fasteners. Then pull the trim piece out and downward.

Next, remove the rear cab pillar trim piece. Gently pull from the top, there are a couple push pins but easily removed by gently pulley outward.

Itay help to remove the rear cab panel, depending on your options, mine just pulled loose

There passenger side uses 3 - 10mm bolts to hold it in place.

After removing all the driver/passenger trim & handles, visors. Gently pull down on the headliner in incremental even movements from rear and side to side. The front should not detach completely. The seat headrests can be used to distribute and support the headliner. Do not let it hang as it may crease and become damaged.
You should now have access to the harness for the cab side 3rd brake light

I used a 3 wire PVC coated jumper to run from inside the cab to the pigtail in the cap. I went through a rubber plug in the floor underneath the amplifier which is underneath the drivers seat. Followed the frame to a strand wires I could zip tie to and ran all the way to the bed where I wired up to the TAB pig tail for the 3rd brake light/dome light.