2018 GMC Sierra 1500 Reliability Report

Power steering cuts out without warning, leaving the wheel very hard to turn at highway speed, over bumps, or in low-speed turns. In some trucks the dashboard and engine also cut out. Repairs, including a replaced steering rack, often fail to stop it. Owners also report the truck pulling left, the steering wheel shuddering at 40 to 55 mph, and tires rubbing the upper control arm at full lock. One crash followed a ball joint pulling out of the control arm on a low-mileage truck.

Two problems dominate. The first is a "Service Trailer Brake System" alarm that sounds over and over, even on trucks that never tow, which owners find dangerously distracting. The second is a "Service Brake Assist" message that comes with a stiff or vibrating pedal and longer stopping distances. Dealers often trace this to a failed brake vacuum pump. Several owners found the problem matched an existing recall but their VIN was not included. One report describes a failed ABS control module.

These reports are a mix, and many repeat problems seen in other categories. The truck surges or bucks when shifted out of park or between gears, and one surge caused a minor collision. Other reports describe shuddering at highway speed and early transmission replacement. Air conditioning condensers and radiators leak. Sunroofs and heated rear windows shatter on their own. Stiff brake pedals with a "Service Brake Assist" message, constant trailer brake warnings, and repeat rear spring repairs also appear.

Internal engine failure is the main theme. Dealers and mechanics find failed lifters, damaged camshafts, a broken connecting rod and metal shavings, and they usually recommend a replacement engine. Before failure, owners notice hesitation, banging or ticking, shaking and reduced power. Several connect their trucks to federal engine investigations or recalls but find their VIN is not covered. One lifter failure came back after an engine replacement. Fractured exhaust manifold bolts and a leaking AC condenser also appear.

Few complaints are filed here, but most involve crashes. In one, the airbags did not deploy in a 35 mph collision and the driver suffered a head injury. In another, the steering wheel cover split at the logo during deployment and injured the driver's wrist. Side airbags also deployed with no crash in a driveway, and one deployment filled the cab with smoke. One owner reports waiting on a recall replacement part with no dealer action.

The front buckle fails to latch or releases after latching. Rear belts stop locking or retracting, and some get stuck between the seat cushions. One failed middle belt left an owner unable to use a child booster seat. Some failures show up soon after purchase, others around 60,000 miles. Dealers usually replace the buckle receptacle or retractor, and owners pay for it.

Sunroof glass shatters on its own while the truck is moving, with no impact, and drops shards into the cabin and bed. Dealers send owners to their insurance company instead of covering it. In one report, the spare tire cable broke and the tire fell out at highway speed and damaged a towed camper. Another describes a brake pedal that turned hard and made an air sound, which led to a crash on a low-mileage truck.