🏷️ Basic Information

Make:

Mitsubishi

Model:

Sigma / Diamante

Production Years:

1991-1995

Platform:

JDM: J-platform; USDM: Mitsubishi Diamante (from 1990.5-1996)

Chassis Codes:

F11A, F12A, F13A, F15A, F17A, F21A, F23A, F25A, F27A (varies by engine and market)

👋 Introduction

Market Position:

The Mitsubishi Sigma (Diamante in many markets) was a large, upscale sedan and coupe positioned as a premium offering for Mitsubishi, competing with established luxury and near-luxury sedans of its era.

Competitive Analysis:

Competed with vehicles such as the Toyota Avalon, Nissan Maxima, Buick Park Avenue, and Ford Taurus SHO in North America, and similar segment vehicles in other markets. It aimed to offer a blend of performance, comfort, and distinctive styling.

Key Features:

Available with advanced features for its time, including multi-link suspension, electronically controlled transmissions, and sophisticated engine management systems. Known for its smooth ride and quiet cabin.

Design Philosophy:

The Sigma/Diamante was designed with a focus on European luxury car aesthetics, featuring a sleek, aerodynamic profile and a sophisticated interior that emphasized comfort and refinement.

Performance Emphasis:

While primarily a comfort-oriented sedan, the V6 engines provided adequate power, and performance variants (like those with AWD) offered a more engaging driving experience.

📋 Manual Details

Coverage Areas:

All models and engines for the 1991-1995 production years

Page Count:

1500+

Manual Type:

Workshop Service Repair Manual

Language:

English

Format:

PDF

Delivery Method:

Instant download link provided upon purchase, also emailed.

Digital Rights Management:

DRM-free, allowing unrestricted printing and use.

📖 Manual Coverage

Systems Covered:

Engine Mechanical, Engine Control System, Engine Coolant, Emission Control Systems, Drive Shaft, Drive Belt, Differential Case Assy, Cylinder Head Assy, Cylinder Head, Cylinder Block Assy, Cooling System, Cooling Fan System, Combination Meter, Clutch Unit, Clutch System, Charging System, Charcoal Canister, Brake System, Brake Pedal, Brake Master Cylinder, Brake Fluid, Brake Booster, Brake Actuator, Body Repair, Steering System, Steering Sensor, Steering Column, Starting System, Starter Switch, Starter Assy, Spiral Cable Sub-Assy, SFI System, Seat Belt Warning System, Seat Belt, Roof Headlining, Receiver Condenser Assy, Radiator Assy, Quarter Window Assy, Pulley Compressor Assy, Power Window Control System, Power Steering Link Assy, Power Steering, Power Mirror Control System, Power Door Lock Control System, Parking Brake Lever, Parking Brake Cable, Parking Brake, Oil Pump, Oil Filter, Manual Transaxle System, Lubrication System, Lighting System, Instrument Panel, Ignition System, Hood, Heater Radiator Assy, Transmission Control Cable, Torque Converter Clutch, Tire & Wheel, Throttle Body Assy, Thermostat, Supplemental Restraint System, Sun Roof System, Sun Roof, Speed Sensor Front, Skid Control Sensor, Shift Lock System, Seat Position Air Bag Sensor, Seat, Roof Drip Side Finish Moulding, Rear Wiper Rubber, Rear Wiper Motor Assy, Rear Wheel Alignment, Rear Suspension System, Rear Suspension, Rear Speaker Assy, Rear Shock Absorber Assy, Rear Seat Belt, Rear Door Window Frame Moulding, Rear Door Glass Weatherstrip, Rear Door, Rear Combination Lamp Assy, Rear Coil Spring, Rear Bumper, Rear Brake, Rear Axle Hub, Rear Axle Beam, Radio Receiver Assy, Yaw Rate Sensor, Wiring Diagrams, Wire Harness Repair, Wiper Rubber, Wiper And Washer System, Windshield Wiper Switch Assy, Windshield Wiper Motor Assy, Windshield Glass, Window Defogger System, Wheel And Tire System, Water Pump Assy, Valve Clearance, Transmission Wire, Transmission Valve Body, Transmission Revolution Sensor, Washer Nozzle, Camshaft Position Sensor, Camshaft, Clutch Start Switch Assy, Clutch Release Cylinder Assy, Clutch Pedal Sub-Assy, Clutch Master Cylinder Assy, Cigarette Lighter Assy, Center Stop Lamp Assy, Center Cluster Module Switch, Center Air Bag Sensor Assy, Curtain Shield Air Bag Assy, Combination Meter, Brake Fluid, Body Repair, Air Bag Systems, Air Conditioning System

Procedures Included:

Detailed sub-steps for repair procedures, troubleshooting, electrical service procedures, complete disassembly and reassembly instructions, diagnostic procedures, component replacement, system adjustments, fluid level checks and changes, filter replacement, lubrication procedures, brake system bleeding, suspension component service, steering system repair, power accessory troubleshooting, HVAC system maintenance, body panel repair, interior trim removal and installation, diagnostic trouble code (DTC) interpretation and resolution, wiring harness repair, emissions system diagnosis and repair, safety system service (SRS), and more.

Technical Depth:

Comprehensive, covering everything from routine maintenance and minor adjustments to major component overhauls and complex diagnostic procedures. Designed for both DIY enthusiasts and professional mechanics.

Diagnostic Coverage:

Includes detailed troubleshooting trees for common drivability issues, electrical system faults, HVAC problems, and more. Covers diagnostic trouble code (DTC) retrieval and interpretation.

Electrical Coverage:

Extensive coverage of the vehicle's electrical systems, including wiring diagrams for all major components, starter system, charging system, lighting, instrumentation, power accessories, and diagnostic procedures for electrical faults.

Body And Interior Coverage:

Detailed procedures for body panel removal and installation, interior trim components, doors, windows, sunroof, seat removal and repair, carpeting, headliner, and dashboard assembly.

Suspension And Steering Coverage:

Comprehensive information on front and rear suspension systems, steering gear, power steering system, wheel alignment specifications, and component replacement (e.g., shocks, struts, bushings, tie rods).

Engine Performance Tuning:

Provides factory specifications for engine performance parameters, enabling diagnosis and correction of issues affecting power output and efficiency.

Troubleshooting Methodology:

Employs a systematic, symptom-based troubleshooting approach, guiding the user through logical steps to identify the root cause of a problem.

📊 Manual Specifications

File Format:

PDF

PDF Features:

Indexed, iPad-ready, searchable text, DRM-free

Print Quality:

Printable (all pages)

Binding Type:

Digital Download

Paper Type:

N/A (Digital)

Accessibility Features:

Indexed for easy navigation, allowing users to quickly find specific information. iPad-ready format ensures compatibility with modern tablet devices.

⚙️ Engine Specifications

Engine Options:

3.0L V6 (6G72) SOHC and DOHC variants, 3.5L V6 (6G74) DOHC variants (depending on market and year)

Horsepower Range:

Approximately 170 HP to 230 HP (depending on engine variant and market)

Torque Range:

Approximately 175 lb-ft to 230 lb-ft (depending on engine variant and market)

Fuel System:

Multi-Port Fuel Injection (MPI)

Engine Management:

Electronic Fuel Injection (EFI) with Knock Control, OBD-I/OBD-II compliance depending on year and market

Engine Layout:

V6 (6-cylinder in a V configuration)

Bore X Stroke:

3.0L: 91.1 mm x 76.0 mm; 3.5L: 93.0 mm x 85.8 mm (approximate)

Compression Ratio:

9.0:1 to 9.5:1 (depending on engine variant)

Cooling System Type:

Pressurized liquid cooling system with belt-driven water pump and electric cooling fan.

Ignition System Type:

Distributorless Ignition System (DIS) or distributor-based systems depending on the specific engine variant and year.

🔧 Transmission

Standard Transmission:

4-speed Automatic Transmission (e.g., F4A51, V4A51) with electronic control; 5-speed manual transmission available on some models.

Optional Transmission:

5-speed Manual Transmission (on select models)

Transmission Features:

Electronically controlled transmission (ECT) with 'Power' and 'Normal' modes on automatic variants. Some models may feature a viscous coupling all-wheel-drive system (often designated 'V-AWD').

Drive Type:

Front-Wheel Drive (FWD) standard; All-Wheel Drive (AWD) optional on select models.

📐 Dimensions

Wheelbase:

Approximately 106.7 inches (2710 mm)

Length:

Approximately 190.2 - 192.5 inches (4830 - 4890 mm) depending on body style and market

Curb Weight:

Approximately 3400 - 3800 lbs (1542 - 1724 kg) depending on configuration

Gross Vehicle Weight Rating:

Typically around 4700-5100 lbs (2130-2313 kg)

Seating Capacity:

5 passengers

🛡️ Safety Features

Safety Ratings:

NHTSA and IIHS ratings vary by year and specific testing protocols. Generally considered a safe vehicle for its era, but specific ratings are not universally available.

Active Safety Features:

Anti-lock Braking System (ABS) available on many models, Traction Control System (TCS) on some higher trims.

Passive Safety Features:

Dual front airbags (standard on most models from 1990s onwards), front and rear crumple zones, side-impact door beams, seatbelt pre-tensioners.

Front Brakes:

Ventilated Disc Brakes

Rear Brakes:

Disc Brakes (Solid or Ventilated depending on model)

Srs Coverage:

Detailed information on airbag system components, sensors, control module, and safety precautions for handling airbag systems. Includes wiring diagrams and diagnostic procedures for SRS faults.

💡 Technology Features

Infotainment Features:

Factory-installed cassette or CD players, AM/FM radio, optional premium audio systems (e.g., Mitsubishi Premium Sound System). Early models may feature analog climate controls.

Driver Assistance Features:

Optional cruise control, power windows and locks, power mirrors. Some higher trims may have had early forms of driver aids, but not typically considered 'advanced' by modern standards.

Connectivity Features:

Limited by era. Primarily focused on audio system connectivity (e.g., antenna for radio). No integrated Bluetooth or USB connectivity.

Climate Control System:

Manual or automatic climate control systems, including air conditioning (A/C) refrigerant charging, compressor, condenser, evaporator, and heater core service procedures.

🔧 Maintenance

Oil Change Interval:

Every 3,000-5,000 miles (4,800-8,000 km) or 3-6 months, depending on driving conditions and oil type used. Refer to manual for exact specifications.

Coolant Change Interval:

Every 30,000 miles (48,000 km) or 2-3 years. Use Mitsubishi Super Long Life Coolant or equivalent.

Timing Belt Replacement:

Approximately every 60,000 - 90,000 miles (96,000 - 145,000 km). Crucial for 6G72/6G74 V6 engines to prevent catastrophic failure.

Engine Oil Specification:

API SG or higher, SAE 10W-30 or 5W-30 (check owner's manual for specific recommendations based on climate)

Transmission Fluid Specification:

Mitsubishi SP-II or ATF-SP II (for automatics). Manual transmission fluid varies, consult manual.

Brake Fluid Specification:

DOT 3 or DOT 4

Common Issues:

Degradation of coolant hoses leading to leaks, potential for head gasket issues on some V6 engines if overheated, wear in suspension components (bushings, ball joints), aging electrical connectors and sensors, intermittent ABS light, automatic transmission solenoid issues.

Oil Filter Part Number Example:

MD356000 (example for some models, consult specific part lookup)

Air Filter Part Number Example:

MR188017 (example for some models, consult specific part lookup)

Tire Size Examples:

P205/70R15, P215/60R15, P215/55R16 (depending on trim level and year)

Wheel Bolt Pattern:

5x114.3 mm (5 lug)

Chassis Lubrication Points:

Details on chassis lubrication points, if applicable, for suspension and steering components.

📚 Vehicle History

Brand Heritage:

Mitsubishi, a Japanese automotive manufacturer with a long history dating back to the early 20th century, known for a diverse range of vehicles from compact cars to SUVs and performance vehicles.

Model Evolution:

The Sigma/Diamante represented Mitsubishi's attempt to capture a larger share of the mid-size to large executive sedan market. It was known for its stylish design and comfortable interior, aiming to provide a more premium experience than previous Mitsubishi offerings.

Production Locations:

Primarily manufactured in Japan. Some later generations of the Diamante may have been assembled in other markets.

Model Notes:

In Japan, the car was known as the Mitsubishi Sigma. In many export markets, particularly North America, it was sold as the Mitsubishi Diamante, often marketed as a premium luxury sedan.

🏆 Awards & Recognition

Recognitions:

The Diamante model often received positive reviews for its styling and comfortable ride in automotive publications of the early to mid-1990s. Specific awards are not widely documented but it was considered a strong contender in its segment.