🏷️ Basic Information

Make:

GMC

Model:

Sonoma

Year:

1990

Platform Code:

GMT400

Generation Designation:

First Generation (1982-1997, though 1990 falls within the significant refresh/introduction of the Sonoma nameplate for GMC's compact truck line, inheriting much from the S-15 Sonoma and its GM siblings like the Chevrolet S-10).

👋 Introduction

Target Audience:

GMC Sonoma owners and independent repair shops seeking professional, dealership-level repair information.

Value Proposition:

Provides exact same information as used by dealership technicians, enabling users to perform maintenance, diagnostics, and repairs accurately and efficiently, saving time and money compared to relying on general guides or professional mechanics for every task.

Differentiation:

Distinguishes itself from generic repair information by offering vehicle-specific, factory-authorized procedures, diagrams, and schematics, ensuring precision and accuracy.

Organization:

Single, easy-to-use PDF manual, eliminating the need to consult multiple physical books.

Content Richness:

Includes step-by-step instructions, detailed diagrams, illustrations, and complete wiring schematics.

Practicality:

Printable pages allow for on-site use in the garage or workshop without risking damage to the original digital file.

📋 Manual Details

Primary Coverage:

All models and all repairs A-Z for the 1990 GMC Sonoma.

Scope:

Vehicle-specific factory-level repair information for technicians and do-it-yourself enthusiasts.

Estimated Page Count:

Not explicitly stated in product information, but implied to be comprehensive, covering all systems.

Type:

Service and Repair Manual

Source:

Factory OEM (Original Equipment Manufacturer) Equivalent

Language:

English

Format:

PDF (Portable Document Format)

Compatibility:

Windows (Vista 32/64, XP, ME, 98, NT, 2000) and Mac compatible.

Accessibility:

Printable, zoomable images, searchable text (typical PDF functionality).

Software Requirements:

Adobe PDF Reader and Winzip (free online).

Download Performance:

Advertised as 'Speed Download'.

📖 Manual Coverage

Powertrain:

Engine, Fuel Service Specifications, Emission Control, Intake/Exhaust/Cooling, Lube, Ignition, Starting, Charging, Auto Transmission, Clutch, Manual Transmission, Transfer Case, Propeller Shaft, Drive Shaft, Differential, Axles.

Chassis:

Suspension, Tire & Wheel, Brake Control, Brakes, Parking Brake, Steering Column, Power Steering.

Body Electrical:

Air Conditioning, Supplemental Restraint System (SRS), Seat Belt, Engine Immobilizer, Cruise Control, Wiper & Washer, Door Locks, Meter, Audio/Visual, Horn, Windshield/Glass/Mirrors, Instrument Panel, Seats, Engine Hood/Door, Exterior & Interior Electrical, Multiplex/CAN Communication.

Maintenance:

Scheduled maintenance, fluid checks and changes, filter replacements, tune-ups.

Diagnostics:

Troubleshooting guides, diagnostic procedures, symptom analysis.

Repair:

Step-by-step repair instructions for all covered systems, including disassembly, component replacement, and reassembly.

Specifications:

Detailed torque specifications, fluid capacities, clearances, diagnostic trouble codes (DTCs) interpretation, wiring schematics.

Depth:

Comprehensive, covering everything from basic maintenance to complex electrical diagnostics and major mechanical repairs. Designed for dealership technicians, indicating a high level of technical detail.

📊 Manual Specifications

File Type:

PDF

Searchability:

Assumed searchable text within the PDF for efficient information retrieval.

Printability:

High-quality, printable pages allowing users to select and print only necessary sections or diagrams.

Image Enhancement:

Ability to blow up images for enlarged viewing and printing.

Binding:

Digital (PDF) - no physical binding. Offers flexibility over traditional paper manuals.

Physical Paper Type:

N/A (Digital format)

⚙️ Engine Specifications

Engine Options:

Likely includes the 2.5L (151 cu in) Tech IV four-cylinder and potentially the 4.3L (262 cu in) Vortec V6 engine options.

Horsepower 2.5L:

Approx. 105-112 hp (specific output varies by tune).

Torque 2.5L:

Approx. 130-135 lb-ft (specific output varies by tune).

Horsepower 4.3L V6:

Approx. 150-165 hp (specific output varies by tune).

Torque 4.3L V6:

Approx. 225-240 lb-ft (specific output varies by tune).

Injection Type:

Likely multi-port fuel injection (MPI) for both engines, or throttle body injection (TBI) for earlier/base configurations. The manual will detail specific system configurations.

Fuel Type:

Unleaded gasoline.

🔧 Transmission

Transmission Options:

Likely a 5-speed manual transmission (e.g., Getrag 260 based) as standard on many models.

Transmission Options:

Optional automatic transmissions, likely the 3-speed THM700R4 or the 4-speed 4L60 automatic transmission for V6 models.

Drivetrain:

Available in 2WD (RWD) and 4WD configurations.

📐 Dimensions

Body Styles:

Standard Cab, Extended Cab.

Bed Lengths:

Short Bed (approx. 6.5 ft) and Long Bed (approx. 7.5 ft) configurations.

Curb Weight:

Varies significantly by configuration, typically ranging from 2,800 to 3,500 lbs (approx.). The manual will provide exact GVWR and curb weights for specific configurations.

🛡️ Safety Features

Crash Test Data:

Limited public crash test data available for this specific model year from organizations like NHTSA. Manual will detail occupant protection systems. Supplemental Restraint System (SRS) information is mentioned.

Braking System:

Front disc brakes, rear drum brakes. ABS (Anti-lock Braking System) may be optional or standard on certain trims/configurations.

Restraint System:

Seat belts (manual will cover adjustment, maintenance, and replacement), Supplemental Restraint System (SRS - Airbag) availability and function (though airbags were less common or optional on many base models in 1990).

💡 Technology Features

Audio System:

Factory-installed AM/FM radio, possibly with cassette player. Options for premium sound systems and CD players may have existed. Manual covers installation, removal, and troubleshooting.

ABS:

Anti-lock Braking System (ABS) available as an option on certain models, particularly rear-wheel anti-lock. Manual will detail its operation and diagnostics.

Multiplex Communication:

The manual mentions 'Multiplex/CAN Communication,' which is noteworthy for a 1990 vehicle. This suggests an early implementation of multiplexing for control systems, likely for functions like lighting or power windows, rather than full CAN bus as we know it today. The manual will explain this system.

🔧 Maintenance

Oil Change Interval:

Typically every 3,000-5,000 miles or 3-6 months, depending on driving conditions. The manual will specify GM's recommended intervals and oil types.

Tire Rotation Interval:

Typically every 5,000-7,500 miles. The manual will provide specific recommendations based on tire type and vehicle load.

Engine Oil Type:

Likely 5W-30 or 10W-30 for gasoline engines. The manual will specify API service classifications and precise viscosity grades.

Transmission Fluid Automatic:

Likely Dexron-III (or equivalent) ATF. Manual will confirm exact specification.

Coolant Type:

Typically a conventional ethylene glycol-based coolant. Manual will specify mixture ratios and recommended types (e.g., green coolant).

Common Problems Engine:

Potential issues include intake manifold gasket leaks (V6), minor oil leaks, and distributor drive gear wear. The manual will guide diagnosis and repair.

Common Problems Suspension Steering:

Ball joint wear, tie rod end wear, and power steering pump leaks can occur over time. Manual covers inspection and replacement.

Common Problems Electrical:

Corrosion in electrical connectors, faulty grounds, and aging wiper motors or power window regulators are possible. The detailed wiring schematics in the manual are crucial for troubleshooting.

📚 Vehicle History

Gmc Truck Legacy:

GMC, as a division of General Motors, has a long history of producing trucks and commercial vehicles. The Sonoma nameplate replaced the S-15 compact pickup, offering a more modern and refined option in its segment.

Sonoma Introduction:

The Sonoma was introduced as GMC's compact pickup truck for the 1991 model year, effectively rebranding and updating the S-15 Sonoma. The 1990 model year represents the final iteration of the S-15 Sonoma platform before the name change.

Manufacturing Locations:

Produced in various GM assembly plants in North America. Specific plant details might not be in the manual but are relevant to historical context.

🏆 Awards & Recognition

Industry Awards:

Information on specific awards for the 1990 GMC Sonoma (or its S-15 predecessor) is not readily available in general historical records. However, the compact truck segment was highly competitive, and GM's trucks generally received positive reviews for utility and capability. The manual itself is an award-winning type of product in terms of its utility to owners.