There are 2 owner-reported electrical system complaints for the 2018 GMC Yukonin NHTSA's database. These are unverified consumer reports and may not reflect confirmed defects.
Keeps showing a service trailer brake system, it does it once in a while but when it does it keeps showing the message after pressing dismiss, I was researching online and apparently there is a lot of people dealing with this same issue and looks like it is a defect from factory.
Side rear brake lights work intermittently, often cutting out and losing all power while driving.
Complaints are unverified consumer reports submitted to NHTSA. A high complaint count may reflect vehicle popularity, not defect severity. Data sourced from NHTSA public records.
Data synced from NHTSA on Apr 25, 2026