Trailer Stability Assist (sometimes called Trailer Sway Control or TSA) is supposed to make towing calmer and safer by detecting sway and selectively applying brakes or reducing engine power. When it malfunctions—false activations, warning lights, or failure to engage—it can be scary and dangerous. If repeated dealer repair attempts haven’t fixed the issue, California’s lemon law may offer remedies. This article explains how TSA failures fit into California’s lemon law framework and how to document your issue so you can make informed next steps.
California Lemon Law for Trailer Stability Assist Failures
Trailer Stability Assist is now standard on many trucks and SUVs sold in California. The system uses sensors to detect sway from a towed trailer and helps stabilize the vehicle-trailer combination. Common complaints include TSA warning lights that won’t clear, aggressive brake pulsing without sway, cutting engine power during normal towing, or TSA becoming unavailable after short drives. Because these issues can affect steering, braking, and confidence while towing, they’re not just annoyances—they can implicate safety and vehicle value.
California’s lemon law (the Song-Beverly Consumer Warranty Act) generally protects consumers when a vehicle has defects covered by the manufacturer’s warranty that a dealer cannot fix after a reasonable number of attempts. There’s a legal “presumption” window during the first 18 months or 18,000 miles: four or more repair attempts for the same issue, two or more attempts for a defect that could cause serious injury or death, or 30 cumulative days out of service may suggest the vehicle is a lemon. Even if your TSA problem falls outside that window, you may still have rights if the defect is substantial, ongoing, and covered by warranty. TSA malfunctions can be treated as safety-related because they involve braking and stability under load.
If the law applies, potential remedies can include a repurchase (often called a buyback), a replacement vehicle, and certain incidental expenses such as towing or rental cars. Which remedy may be available depends on factors like repair history, mileage offsets, and warranty coverage. Arbitration or manufacturer programs may be options, and different timelines and procedures can apply. Because each situation is fact-specific, it’s wise to review your records and speak with a professional. ZapLemon can help you understand how the lemon law might apply to a TSA failure without making any guarantees about your particular outcome.
How to Document Trailer Stability Assist Failures
Good documentation can make or break a lemon law claim. Start by capturing the basics each time the TSA acts up: date, time, outside temperature, road type, speed, whether a trailer was attached, trailer weight (if known), load distribution, and any dash messages. Note if you used a weight distribution hitch, sway control bars, or an aftermarket brake controller. Photos or short videos of warning lights and messages can be helpful, but prioritize safety—pull over before recording anything. If the issue only appears when towing, consider bringing the trailer for a safe, scheduled test drive with the dealer (if permitted).
Always take the vehicle to an authorized dealership for diagnosis and repair while the manufacturer’s warranty (including any certified pre-owned coverage) is active. Ask the service advisor to describe your concern in your own words on the repair order, and request copies of every repair order and final invoice. Check that they include your complaint, the technician’s findings, diagnostic codes, software versions, parts replaced, and dates in and out of service. If the dealer updates software or performs a “relearn,” make sure that’s documented. Keep your own timeline of days the vehicle is unavailable due to repairs.
Round out your file with manufacturer communications and public information. Search NHTSA for recalls and complaints and ask the dealer about technical service bulletins (TSBs) related to TSA, ABS, steering angle sensors, yaw/accelerometer sensors, wheel speed sensors, trailer wiring modules, or brake system updates. If the dealer suggests the problem is caused by accessories, note whether the accessories are OEM or aftermarket and whether they meet the manufacturer’s towing specs. None of this is legal advice, but comprehensive records typically help professionals evaluate warranty rights. If you think your TSA issue is ongoing despite multiple attempts, consider a consultation to review your documentation and options.
This article is for general informational purposes only and is not legal advice. Reading it does not create an attorney-client relationship, and past results do not guarantee a similar outcome. Laws and timelines can change, and your facts matter. If you believe your vehicle may qualify as a lemon, contact ZapLemon at [phone number] or [website]. We can review your situation, explain your options, and discuss next steps in a free, no-obligation consultation.