On any grade of 5 percent or more, Hill Start Assist automatically engages the GMC Sierra’s brakes for 1.5 seconds or until the gas pedal is pressed. This keeps the truck from rolling rearward and helps in trailering situations like climbing a boat launch.
Tow/Haul mode, activated by a button on the shift lever, modifies the standard six-speed transmission’s shift mapping to take full advantage of the Sierra’s new EcoTec3 engines. Under acceleration, shift points are higher for more power, while downshifts are initiated earlier to promote engine braking, reducing brake wear.
With Tow/Haul mode engaged, Sierra’s Trailer Grade Braking is activated when the driver lightly applies the brakes. This feature initiates downshifts to assist with braking on long downgrades. In addition to slowing the vehicle more efficiently, Auto Grade Braking can reduce brake rotor temperatures by 100 degrees Celsius during a braking event.
For drivers who prefer full control over their truck’s shifting, improved TapShift controls on the shift lever are backed by a patent-pending shift algorithm that improves shift response time by up to 60 percent compared to previous systems. When TapShift controls are in use, Sierra’s Trailer Grade Braking is deactivated because the driver is manually controlling gearshifts.
Trailer Sway Control works with the Sierra’s standard StabiliTrak to provide the driver with additional assistance when towing a trailer. When it senses trailer sway, it intervenes with braking and/or reduced engine power to bring the trailer under control and keep it on its intended path. It also uses the electric trailer brakes when a trailer is plugged into the standard wiring harness of the truck.
Sierra owners can fine tune trailer braking performance from the driver’s seat. With an available high-mounted Integrated Trailer Brake Controller, the driver can adjust gain – the level of output to the electric trailer brakes – via buttons to the left of the steering wheel. System information is displayed in the Driver Information Center on the instrument cluster.
The Trailer Brake Controller allows owners to quickly modify trailer braking force based on the weight of a trailer. For example, a driver delivering heavy building supplies could adjust the controller to lower trailer gain for an empty trailer on the return trip, minimizing the chance of trailer wheel lock-up.
The 2014 Sierra’s optional Max Trailering Package allows trailering up to a class-leading 12,000 pounds with the optional 6.2L EcoTec3 V-8 engine. The Max Trailering Package is available on 2WD and 4WD V8 crew cab and double cab models and includes:
- Trailering package with seven-pin and four-pin connector
- Enhanced cooling
- Automatic locking rear differential
- Heavy-duty 9.75-inch rear axle with 3.73 ratio
- Increased-capacity rear leaf springs
- Revised shock tuning for increased control
- Integrated trailer brake controller.
Sierra’s 5.3L EcoTec3 V8 offers maximum trailering of 11,500 pounds, more than any competitor. Sierra’s 4.3L EcoTec3 V6 can trailer up to 7,200 pounds, 500 pounds more than a Ford F-150 3.7L pickup and 700 pounds more than a Ram 1500 3.6L.