The 1991 Chevrolet Lumina is a mid-size sedan built on the versatile GM W-body platform. Designed as a domestic competitor in a segment populated by models like the Ford Taurus and Toyota Camry, the Lumina offered a focus on comfort and interior space. It was available with a choice of two V6 engines: a 2.5L (151 cu in) Tech IV V6 producing approximately 119 horsepower, and a 3.1L (191 cu in) High Output V6 generating around 140 horsepower. Both engines utilized port fuel injection and were primarily paired with a 4-speed automatic transmission, the 4T60-E, known for its electronic control and adaptive shift points. The Lumina’s engineering quality and reliability were characteristic of Chevrolet’s offerings during this era, aiming to provide a practical and comfortable transportation solution. This comprehensive manual serves as an essential resource for the service and repair of the 1991 Chevrolet Lumina. It covers a wide array of systems, including detailed procedures for engine mechanical and electrical components, transmission and drivetrain, brakes, suspension, steering, and the complete electrical and electronics systems. Additionally, it addresses HVAC, body and chassis work, and provides guidance on routine maintenance and major repairs. The manual offers in-depth troubleshooting, diagnostic information, and technical specifications, making it invaluable for owners, mechanics, and technicians seeking to maintain or restore the vehicle's optimal performance and longevity.