Water Leaks into Tacoma Cabins Through 3rd Brake Light

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Water can leak into the cabin of a 2016-2018 Tacoma because Toyota did a terrible job sealing the 3rd brake light mounted above the bed. There's a gap between the LED light and the body that collects water. Meanwhile a cheap brittle gasket does little to stop that water from leaking into the truck.

The problem only affects double cab versions of the truck, as the access cab uses a different light assembly.

Water Leaks Always Cause a Lot of Damage

Even a small amount of water can do significant damage. If an owner doesn't spot the leak right away or the water drips behind trim panels, there's concern about mildew forming or electrical wiring fizzling out.

As the leak worsens, it stains the headliner and can pool on the back seats.

An overly complicated and costly repair

The "high mount stop lamp" is mounted from inside the truck which means to service or replace it, you need to remove the b-pillars and drop the headiner. That's a heck of a lot of work just to access two 10mm screws holding the darn thing in place.

Covered under the standard warranty

The work to replace the light is only covered under the standard 3 year / 36,000 mile warranty. In July of 2018, Toyota released service bulletin #0055-18 titled Water Leak at Rear of Cab -Center High Mount Stop Lamp that outlines the steps needed to confirm and fix the problem.

The service bulletin only applies to specific VIN ranges of the 2016-2018 Tacoma double cab.

For everyone else it's at least $500

Once you're out-of-warranty the light is deceptively expensive unless you want to replace it yourself. On average the cost of repair is around $500, mostly for labor, as the part MSRPs for around $150.

The good news is while the original OEM part (#81570-04040) seems to just be held on with double-sided tape and the faintest hint of a foam gasket, the newer version from Toyota (#81570-04051) comes with a much thicker gasket.

As shown by a post in the Tacoma World forum:

it’s a thicker foam gasket. Original looks like it was just thick double sided tape. Barely holding on up top, leaking in two places.

A hand holds the original light assembly (left) next to the new (right) to show a difference in gasket size
The difference in gasket size as shown by tacomaworld.com user suaveflooder

Other repair options

Some say if they're going to go through the trouble of dropping the headliner they'll just replace the whole assembly with a fancier 3rd party option. While others try to DIY it with a bead of clear silicone sealant around the outside of the light, hoping that'll stop the leaks.

Generations Where This Problem Has Been Reported

This problem has popped up in the following Toyota generations.

Most years within a generation share the same parts and manufacturing process. You can also expect them to share the same problems. So while it may not be a problem in every year yet, it's worth looking out for.

  1. 3rd Generation Tacoma

    Years
    2016–2021
    Reliability
    70th of 81
    PainRank
    14.73
    Complaints
    241
    Continue

What Owners Say About This Problem

3rd brake light over torqued at factory resulting in defective seal and eventually cracked light fixture. This results not only in electrical issue but serious leaking into cabin - affecting rear seat, roof, and flooring. Leak noticed after rain storms and noticing wet floor/seats and damp floors.

Rain and car wash water will come in the cabin of the truck due to a lose rubber gasket that was not fitted properly to the truck bed light. I also had Toyota check for rust in the cabin once they took the piece off.

Water came in through the back of the cab from the outside cab light I noticed it while going through a touchless drive through car wash. The water soaked through on the headliner and seat leaving a water stain and possible mold. I took the car in to a Toyota dealership and it was confirmed that the water was coming through the cab light on the outside of the truck. This problem was posted on Toyota's bulletin by other 2017 Tacoma owners.

OK, Now What?

Maybe you've experienced this problem. Maybe you're concerned you will soon. Whatever the reason, here's a handful of things you can do to make sure it gets the attention it deserves.

  1. File Your Complaint

    CarComplaints.com is a free site dedicated to uncovering problem trends and informing owners about potential issues with their cars. Major class action law firms use this data when researching cases.

    Add a Complaint
  2. Notify CAS

    The Center for Auto Safety (CAS) is a pro-consumer organization that researches auto safety issues & often compels the US government to do the right thing through lobbying & lawsuits.

    Notify The CAS
  3. Report a Safety Concern

    The National Highway Traffic Safety Administration (NHTSA) is the US agency with the authority to conduct vehicle defect investigations & force recalls. Their focus is on safety-related issues.

    Report to NHTSA