Sealing An Upper Brake Light Crack On A 2017 Chevrolet Cruze LT

Hello everyone, Mitchell here.

Today I noticed that there was a lateral crack on my 2017 Chevrolet Cruze LT’s centre high mount stop lamp (CHMSL), or upper brake light. My suspicion is that it occurred after visiting an automatic car wash yesterday, which I went to mainly to clean the underside of the vehicle in preparation to have it undercoated shortly, as I have been spending much time driving on Gravel Roads recently.

Here is a close up of the crack as seen in the last photo
A wide view of my car’s rear window… You can clearly see the crack on the upper brake light housing on the left

Since my car has over 70 000 km, I’m now out my three year all inclusive warranty so I’m left with either having to replace the assembly of this light, which is likely a couple hundred dollars, or I can attempt a stop gap solution first. Since the car is currently leased, and I haven’t decided if I am going to keep it at the end of the lease, I’d rather attempt a stopgap solution first that will hopefully keep the plastic sealed and prevent water from getting inside the brake light, and ultimately into the car, or worse the trunk, where the battery on this car is located. This brake light assembly was subject to a GM bulletin for 2016 and 2017 models for a separate issue with faulty gaskets that can leak into the batter compartment. However, this is a separate issue not related to that.

Anyway, the stop gap solution I am going to try involves taking some silicone, and running a very light layer along the crack to seal it from weather. This is not a perfect solution, and will likely wear off over time and would then have to be reapplied. Since we’re headed into fall here in Ontario, I’m not likely to wash the car many more times before spring. Anyways, lets get on with this. Keep in mind that this tutorial is applicable to any 2nd generation Chevrolet Cruze Sedan, not just my specific model year and trim level.

Materials you’ll need

  • Silicone – transparent is preferred since it won’t be overly noticeable unless you’re very close. In this case I used a tube gun as pictured
  • Tape – so that you don’t make a mess
    I used painters tape since it’s easy to apply and remove

    The brand of silicone lube used. Did not realize I had the french label facing up until after I took the picture
The silicon in the tube gun ready to apply


  1. Take your tape and apply it to either side of the crack, making sure to follow the corner of the light assembly down to the rear window.
  2. Open the silicone tube, and put a small, maybe a little bigger than a pea sized drop of silicone on your finger
  3. Now trace the crack from the top (roof side edge) downwards until you reach the rear window
  4. Remove the tape, and using a piece of paper towel or a shop towel, wipe away any silicone that ended up on the rear window, if applicable
























And there you go, the crack is patched.

























I will update this post after it rains tonight and let you know if I have a leak or not!

Update: No leak in the car after the rainstorm last night. I do however, suspect that this crack is not in an overly important spot so it’ll likely be fine indefinitely. As well, using a Q-tip may help to fill the crack in where your fingers cannot reach (as the picture above shows, there is a hole in the sealing below the window level and also the entire roof side (which likely couldn’t be reached by Q-tip either)