Market Position:
Targeted at DIY enthusiasts and independent repair shops seeking authoritative, factory-derived information for the 1991 GMC Sonoma.
Competitive Analysis:
Offers a modern, convenient, and licensed alternative to outdated printed manuals. Emphasizes ease of access and comprehensive coverage compared to generic repair guides.
Key Features:
Officially licensed content, OE material derivation, year-long access, multi-device compatibility, extensive system coverage, detailed diagnostic procedures.
Systems Covered:
Engine Mechanical, Fuel System, Cooling System, Lubrication System, Ignition System, Emission Control Systems, Clutch, Manual Transmission, Automatic Transmission, Transfer Case (if applicable), Driveshaft, Axles, Suspension (Front and Rear), Steering System, Brakes (Front and Rear), Wheels and Tires, Body (Interior and Exterior), HVAC System, Electrical System (Wiring Diagrams, Components), Lighting, Instrumentation, Audio System, Security System
Engine Mechanical Coverage:
Detailed information on engine disassembly, assembly, component specifications (pistons, rings, bearings, valves, camshafts), timing procedures, cylinder head refurbishment, and troubleshooting.
Electrical System Coverage:
Comprehensive wiring diagrams for all vehicle systems (engine control, lighting, charging, starting, accessories, HVAC). Includes component locations, testing procedures for sensors and actuators, and troubleshooting flowcharts.
Procedures Included:
Routine Maintenance, Scheduled Maintenance, Diagnosis and Troubleshooting, Component Removal and Installation, Component Reassembly and Adjustment, Torque Specifications, Fluid Capacities and Specifications, Electrical System Diagnosis, Wiring Harness Repair, Body Panel Repair, HVAC System Servicing, Brake System Bleeding and Repair, Suspension Alignment Procedures, Engine Overhaul Procedures, Transmission Service and Repair
Troubleshooting Procedures:
Systematic diagnostic procedures for common drivability issues, electrical faults, and mechanical problems, often presented in a step-by-step format with symptom-to-cause tables.
Drivetrain Repair Procedures:
Detailed steps for clutch replacement, manual transmission overhaul, automatic transmission service, differential inspection and service, driveshaft and U-joint replacement.
Suspension Steering Repair Procedures:
Ball joint replacement, tie rod end replacement, wheel bearing service, shock absorber/strut replacement, power steering pump and gear replacement, alignment specifications.
Technical Depth:
Comprehensive; covers everything from basic oil changes and fluid checks to advanced engine diagnostics, complete powertrain rebuilds, and detailed electrical troubleshooting.
Technical Depth Engine:
Deep dive into engine building and rebuilding, including machining specifications, clearances, and assembly sequences for all internal engine components.
Technical Depth Electrical:
In-depth electrical diagnostics, including testing of ECUs, sensors (e.g., MAP, TPS, O2 sensors), ignition coils, fuel injectors, and related wiring circuits. Troubleshooting of body control modules and accessory circuits.
Wheelbase Std:
Approx. 108.3 inches (2750 mm)
Wheelbase Long:
Approx. 117.9 inches (3000 mm)
Overall Length Std:
Approx. 179.8 inches (4567 mm)
Overall Length Long:
Approx. 195.3 inches (4960 mm)
Curb Weight Est:
3,500 - 4,500 lbs (1588 - 2041 kg), varies by configuration.
Gross Vehicle Weight Rating Gvwr Est:
4,700 - 5,300 lbs (2132 - 2404 kg), depending on configuration.
Oil Change Interval Gasoline:
Every 3,000-5,000 miles or 3-6 months, depending on driving conditions and oil type used.
Engine Coolant Flush Interval:
Every 30,000 miles or 2-3 years.
Automatic Transmission Fluid Change Interval:
Every 30,000-60,000 miles, or as per manual based on severe usage.
Engine Oil Spec V6:
API SG or SH, SAE 5W-30 or 10W-30 (check owner's manual for specific temperature ranges).
Engine Coolant Type:
Ethylene glycol-based antifreeze, typically a green formulation (e.g., GM P/N 1052850 or equivalent).
Brake Fluid Type:
DOT 3 brake fluid.
Power Steering Fluid Type:
Dexron III (or equivalent) or specific power steering fluid.
Transfer Case Fluid Spec 4X4:
GM Part No. 1051749 or equivalent, or Dexron III for some models.
Known Issues:
Common issues include early 4L60 automatic transmission failure (overheating, worn clutch packs), fuel pump failure, intake manifold gasket leaks, distributor gear wear (leading to oil pump issues on 4.3L V6), and potential rust issues in certain climates.
Suspension Components:
Ball joints and control arm bushings can wear over time, leading to clunking noises and steering looseness.
Brake System Wear:
Brake pad and rotor wear is standard, but rear drum brake adjustment and wheel cylinder leaks can occur.
