1990 GMC C1500 Service and Repair Manual

1990 GMC C1500 service and repair manual — a detailed, factory-style reference for maintenance, diagnostics, and repair. Use it to confirm correct procedures, specifications, and system coverage before you start work.

Designed for technicians and DIY owners, this manual helps you troubleshoot accurately, follow step-by-step repair procedures, and reference wiring diagrams and system sections quickly while you work.

What’s included

• Step-by-step repair procedures and service information
• Specifications and reference data (where provided)
• Wiring diagrams and electrical sections
• Powertrain, brakes, steering, suspension, HVAC and more

Trims covered

• Sierra SLE Standard Cab Pickup 2-Door
• Sierra Extended Cab Pickup 2-Door
• Sierra SLE Extended Cab Pickup 2-Door
• Sierra SLX Extended Cab Pickup 2-Door
• Sierra SLX Standard Cab Pickup 2-Door
• Sierra Standard Cab Pickup 2-Door

Engines covered

• 5.0L 305Cu. In. V8 GAS OHV Naturally Aspirated
• 6.2L 379Cu. In. V8 DIESEL OHV Naturally Aspirated
• 4.3L 262Cu. In. V6 GAS OHV Naturally Aspirated
• 5.7L 350Cu. In. V8 GAS OHV Naturally Aspirated

Index / Table of contents

• Body
• Brakes
• Chassis Electrical
• Driveline
• Engine Cooling
• Engine Electrical
• Engine Mechanical
• Engine Performance & Emission Controls
• Fuel System
• General Information & Identification
• Heating, Ventilation, & Air Conditioning
• Hybrid & Electric Vehicle Systems
• Steering
• Suspension
• Transmission, Clutch, & Transfer Case
• Wiring Diagrams