After trying 2 new 3rd brake lights i determined it was the seal on the window that was leaking.
F150 third brake light leak fix.
Start by removing the two screws holding the brake light to the cab.
Unscrew the two mounting screws visible on the front of the old brake light.
Once you do this.
Examine the foam rubber gasket where you saw bubbles and you may see why it was leaking.
I bought this peel and stick variety and it worked.
The fix is simple and will only take about 20 minutes.
The most common fix that people seem to do is to permanently seal the third brake light assembly to the back of the cab with an adhesive such as glue or urethane.
Fixing an f 150 third brake light leak replacement gasket.
The only part required is a replacement gasket.
Does your back window leak in your f150.
Lift the housing away and twist the light sockets out of the brake light housing.
I didn t feel like.