General Motors (GM) has confirmed a serious safety defect affecting certain 2019–2024 Chevrolet Silverado Medium Duty trucks. This issue involves the brake pressure sensor assembly, which may allow brake fluid to leak into the electrical components of the brake pressure switch. Over time, the defect can lead to short circuits, loss of brake system function, and even under hood fires, creating a significant risk of property damage and personal injury.
What Models Are Affected?
The following Chevrolet Silverado Medium Duty trucks are included in this safety defect:
- 2019 Chevrolet 6500
- 2019–2024 Chevrolet Silverado 4500
- 2019–2021, 2023–2024 Chevrolet Silverado 5500
- 2019, 2021–2024 Chevrolet Silverado 6500
Trucks produced before 2019 use a different brake sensor design and are not affected. Certain 2024 Silverado Medium Duty models built with a brake switch wire harness that includes silicone sealant are also excluded.
Why This Is a Safety Concern
If brake fluid leaks past the diaphragm seal into the electrical portion of the brake pressure sensor:
- The switch and fuse can short circuit.
- The circuit may generate excessive heat, leading to a fire risk.
- A fire can occur even when the vehicle is parked and unattended.
This is not only a performance issue but a direct safety hazard for owners and the public.
Chronology of Events Leading to the Defect Finding
The journey to identifying this defect spans several years, beginning with earlier issues and continuing into 2025:
- April 13, 2023 – GM issued NHTSA Recall 23V-266 addressing zinc sealant fragmentation in brake pressure sensors that could cause brake fluid leaks and under hood fires.
- October 11, 2024 – GM’s quality team received a report of unintended brake pump activation in a 2023 Silverado Medium Duty truck that was not part of the earlier recall. The issue was escalated through the Speak Up For Safety (SUFS) program.
- November 24, 2024 – GM opened a formal investigation after discovering brake fluid in the wiring harness of the newer sensor design.
- December 18, 2024 – Another field report surfaced involving a 2021 Silverado truck already repaired under the 23V-266 campaign. GM’s analysis confirmed fluid intrusion.
- January 2025 – Additional warranty-returned parts tested positive for brake fluid contamination in the harness.
- March 3, 2025 – GM and International Motors partnered with Akron Rubber Development Lab (ARDL) for material analysis.
- April 24, 2025 – Testing revealed that the rubber diaphragm was degrading due to the supplier’s use of an unauthorized chemical that reacted with brake fluid.
- April 30, 2025 – GM identified one confirmed fire among 160 reports and began deeper field analysis.
- May 28, 2025 – GM inspected the affected vehicle and concluded the fire was linked to the defect.
- June 5, 2025 – GM’s Safety Field Action Decision Authority (SFADA) determined a safety defect existed in 2019–2024 Silverado Medium Duty trucks.
The Cause of the Safety Defect
Investigations revealed that a supplier used an unauthorized chemical in the rubber diaphragm of the brake pressure sensor assembly. This material degraded when exposed to brake fluid, allowing leaks into the sensor’s electrical system and creating the potential for fires.
Warning Signs Owners May See
Drivers may notice a “Service Brake System” warning light on the dashboard as the defect develops. GM advises that vehicles should be parked outdoors and away from buildings until the problem is corrected.
The Fix for Silverado Owners
GM’s remedy involves replacing the brake pressure switch wire harness with an improved design.
- Interim owner notifications were mailed on July 29, 2025.
- A second notification will be sent once parts are fully available.
- Vehicles that were previously repaired under Recall 23V-266 will also require the updated repair.
GM has assigned this campaign number N242482680, and the NHTSA campaign number is 25V-390.