2005 CHEVY SILVERADO AND GMC SIERRA HYBRID MODELS DELIVER INNOVATIVE FUEL SAVINGS TECHNOLOGY AND LEGENDARY GM TRUCK PERFORMANCE

Introduced during the 2004 model year, Chevy Silverado and GMC Sierra Hybrid models provide General Motors fleet and commercial customers with yet another option when considering full-size pickup choices.  The Hybrid Silverado and Sierra 1500 models promise up to 13 percent improvement in fuel economy, but they return all the performance and capability that have made these trucks legendary.

The hybrid option is available on two- and four-wheel-drive Extended Cab Silverado and Sierra models. They are available in limited quantities to retail customers in California, Washington, and Oregon for the 2005 model year.

The Vortec 5300 V-8 engine delivers 295 horsepower (220 kw) and 335 lb.-ft. (463 Nm) of torque – the same as its non-hybrid counterpart. Yet there’s something Silverado and Sierra Hybrid provide that standard models do not: these trucks are essentially mobile power-generating stations, with four 120-volt/20-amp electrical auxiliary power outlets (APO). The power outlets are located under the rear seat of the cab and in the pickup bed. Customers can conveniently operate power equipment without taking up the bed space typical portable generators would use.

Key hybrid components and systems

Starter Generator/Torque Converter

A key contributor to the Hybrid’s fuel efficiency is its ability to automatically stop and restart the engine under different operating circumstances. Instead of a conventional starter motor and alternator, Hybrid pickups use a compact 14-kw electric induction motor or starter generator integrated in a patented, space-efficient manner between the engine and transmission. The starter generator provides fast, quiet starting power and allows automatic engine stops/starts to conserve fuel. It also smoothes out any driveline surges; generates electrical current to charge the batteries and run auxiliary power outlets; and provides coast-down regenerative braking, as an aid to fuel economy.

The starter generator includes a rotor and stator, housed inside the transmission bell housing. The stator is attached to the engine block and incorporates high efficiency/smaller package-size coils formed by laser-welding copper bars together, instead of winding with copper wire. The rotor bolts directly to the engine crankshaft and spins inside the stator. Current flowing through the stator’s electric windings generates magnetic forces in the rotor, which cause the rotor to turn, starting the engine. The starter generator is in series with the engine, connected directly to it, so that anytime the engine is turning, the starter generator is turning and vice versa.

The starter generator and torque converter are mounted in a concentric arrangement between the engine and transmission, without requiring additional powertrain length. This allows the powertrain to be aligned in the same position as in other GM full-size pickups. A package-efficient 258-mm diameter torque converter, providing driveability comparable to a standard 5.3L/automatic transmission pickup, is key to the compact design. An auxiliary transmission oil pump helps the automatic start feature by assuring sufficient line pressure to allow torque transfer immediately upon driver command, when the engine is started.

Electro-Hydraulic Power Steering System

A uniquely designed, engine-independent electro-hydraulic power steering (EHPS) system provides variable-effort power steering, even when the engine shuts off to conserve fuel. The EHPS “powerpack” integrates an electric motor, a hydraulic pump and an electronic control module; it is powered by the truck’s 42-volt battery pack.

The EHPS also provides power assist for the brake system’s Hydroboost hydraulic brake booster. The brake system includes a unique 1800-psi pressure valve, a long stroke 34-mm diameter master cylinder, and a pedal position sensor, and it provides a 6.4:1 pedal ratio.  

Energy Storage Module

The three valve-regulated lead-acid batteries store power for the 42-volt system. The “deep-cycle” batteries employ absorbent glass mat technology, specifically designed for hybrid vehicles, and are tailored to GM performance requirements. Lead-acid batteries are less costly to replace than nickel-metal hydride batteries, have a 50- to 55-amp-hour capacity and a projected four-year lifecycle.

The batteries are stored in a single energy box that is mounted under the rear seat. They power only the EHPS and the starter generator. A conventional 12-volt under-hood battery powers all the other normal electrical items, such as lighting, driver information center and infotainment system.

Starter Generator Control Module

The starter generator control module (SGCM) controls the flow of torque/energy into and out of the starter generator. Overall, the SGCM controls the starter generator’s engine cranking, torque control, speed control and torque smoothing/active damping functions. It also controls the accessory power module, which generates four types of power: 14-volt DC, 42-volt DC, 120-volt AC and 42-volt AC for the starter function.

In the basic, three-phase inversion/conversion process, 42-volt DC is converted to AC for starting and, conversely, AC is converted to 42-volt DC for recharging. In addition, 14-volt power is converted to 42-volt for jump-starting; 42-volt power is converted to 14-volt for the alternator function; and 42-volt power is converted to 120 volts AC for powering the electrical outlets.

Advanced safety

A passenger-sensing system and dual-level air bags are an integral part of all Silverado and Sierra models, including theHybrid. The system automatically deactivates the passenger-side front air bag under certain conditions to help protect smaller occupants.

Dual-stage frontal air bags are designed to help reduce the risk of air bag-induced injury. When the air bag system’s control unit detects an impact, it determines whether the crash is severe enough to trigger a deployment, and whether the primary amount of inflation is sufficient. The primary stage alone will deploy in most frontal impacts requiring the supplemental protection of an air bag, while a secondary stage is designed to deploy in more severe frontal collisions.

More cabin comfort and convenience

Silverado and Sierra Hybrid's advanced multiplexed electrical architecture enables the driver information center to monitor and report on as many as 34 system functions, including service indicators for "Ice Possible" and "Door Ajar," as well as feedback on the operation of the hybrid system. Available redundant steering-wheel controls allow owners to personalize several functions and safely access infotainment options and provide easy access to the OnStar system. A standard automatic temperature control, dual-zone heating, ventilation and air conditioning (HVAC) system provides outstanding comfort.