The 1990 Buick Century represents a solid offering in the mid-size sedan segment, built on the versatile GM W-body platform. Designed with families and commuters in mind, it prioritizes a comfortable ride and a spacious interior, characteristics that defined Buick's reputation for refined motoring. This generation of the Century, sharing its foundation with models like the Chevrolet Lumina and Pontiac Grand Prix, aimed to blend practicality with a touch of premium appeal, making it a competitive choice against rivals such as the Ford Taurus and Dodge Aries. Its engineering emphasized reliability and a quiet driving experience, reflecting Buick's established brand identity. This comprehensive service and repair manual provides detailed information for the 1990 Buick Century, covering all major systems and components. Within its extensive digital content, you will find step-by-step procedures for routine maintenance, in-depth troubleshooting guides, diagnostic routines, and complete repair instructions for everything from engine rebuilds to electrical system fixes. The manual details specifications for the 3.1L V6 and 2.5L 4-cylinder engines, the 3-speed automatic transmission, braking, suspension, steering, and HVAC systems. It is an essential resource for owners and technicians seeking to maintain, diagnose, and repair this vehicle accurately and efficiently. 🏷️ Basic Information Identification Make: Buick Model: Century Year: 1990 Codes Platform: GM W-body (2nd Generation) 👋 Introduction Market Position Positioning: Mid-size sedan targeting families and commuters, emphasis on comfort and value. Competitive Analysis Competitors: Ford Taurus, Chevrolet Lumina, Dodge Aries/Spirit. Key Features Features: Comfortable ride, spacious interior for its class, front-wheel drive. Manual Advantage Advantage: Official licensing and OE data derivation ensures accuracy and completeness over unofficial guides. 📋 Manual Details Coverage Areas Coverage: Comprehensive service and repair for 1990 Buick Century Manual Type Type: Service and Repair Manual Software Language Language: English Format Format: Digital Download (PDF-like access via web browser) Page Count Page Count: Full factory-derived content (estimated 1000+ pages equivalent) 📖 Manual Coverage Systems Covered Engine: 3.1L V6 (RPO LHO), 2.5L 4-Cylinder (RPO LBO) Engine Management: ECM diagnostics, fuel injection, ignition system, emissions control Transmission: 3-speed Turbo-Hydra-Matic 125C automatic transmission Drivetrain: Front-wheel drive, transaxle, CV joints, axle shafts Brakes: Front disc, rear drum, parking brake, ABS (if equipped) Steering: Power steering system, steering column, tie rods Suspension: Front MacPherson struts, rear independent suspension, shock absorbers, springs Electrical: Battery, charging system, starting system, lighting, instrumentation, body controls, power accessories HVAC: Heating, ventilation, and air conditioning system components and operation Body And Chassis: Body panel removal/installation, doors, windows, interior trim, frame structure Procedures Included Maintenance: Oil changes, filter replacements, fluid checks and top-offs, tune-ups Troubleshooting: Diagnostic procedures for common symptoms, wiring diagrams for fault tracing Repair: Component removal, disassembly, inspection, repair, and reassembly for all major systems Diagnostics: Step-by-step diagnostic routines, component testing procedures Technical Depth Depth: Factory-level detail, covering complete engine rebuilds to simple bulb replacement 📊 Manual Specifications File Format File Format: Web-based access, likely HTML or similar, optimized for browser display Print Quality Print Quality: N/A (Digital format; printable pages are digitally rendered) Binding Type Binding Type: N/A (Digital format) Paper Type Paper Type: N/A (Digital format) ⚙️ Engine Specifications Primary Engine Engine 1: 3.1L (189 ci) V6 (RPO LHO) Engine 1 Configuration: 90-degree V6, Overhead Valves (OHV) Engine 1 Horsepower: 140 hp @ 4800 rpm (approx.) Engine 1 Torque: 170 lb-ft @ 3200 rpm (approx.) Optional Engine Engine 2: 2.5L (151 ci) 4-Cylinder (RPO LBO) Engine 2 Configuration: Inline-4, Overhead Valves (OHV) Engine 2 Horsepower: 110 hp @ 4800 rpm (approx.) Engine 2 Torque: 135 lb-ft @ 2400 rpm (approx.) Fuel System Fuel Delivery: Multi-Port Fuel Injection (MPFI) Fuel Type: Unleaded gasoline, 87 octane (87 AKI) minimum recommended Engine Management ECU Type: GM ECM (Electronic Control Module) 🔧 Transmission Standard Transmission Type: THM 125C (Turbo-Hydra-Matic 125C) Transmission Gears: 3-speed automatic Transmission Fluid: Dexron-III Automatic Transmission Fluid (ATF) Features Drive Layout: Front-wheel drive (FWD) Transaxle Components: Integrated transmission and differential assembly 📐 Dimensions Exterior Wheelbase: 107.5 inches (2730 mm) Length: 190.7 inches (4844 mm) Width: 68.9 inches (1750 mm) Height: 54.8 inches (1392 mm) Weights Curb Weight: Approx. 2900-3100 lbs (1315-1406 kg), varies by engine and equipment 🛡️ Safety Features Ratings NHTSA Driver Front Impact: 4-star (1990 model year testing) NHTSA Passenger Front Impact: 4-star (1990 model year testing) Active Features ABS: Optional Anti-lock Braking System (ABS) on front wheels. Passive Features Airbags: Driver-side airbag standard. Seatbelts: Front: Automatic shoulder belts. Rear: Lap and shoulder belts. 💡 Technology Features Infotainment Audio System: Factory AM/FM stereo with cassette player, optional CD player. Basic speaker systems. Driver Assistance Cruise Control: Optional speed control (cruise control). Connectivity OBD Interface: OBD-I diagnostic port for engine management system data retrieval. 🔧 Maintenance Service Intervals Oil Change Interval: Every 3,000 miles or 3 months, whichever comes first (traditional interval for this era). Transmission Fluid Change: Check every 15,000 miles, change/flush as needed or every 30,000-45,000 miles based...