🏷️ Basic Information

Make:

Mitsubishi

Model:

Diamante

Model Alternate Name:

Sigma (Japan market)

Model Years Covered:

1991, 1992, 1993, 1994, 1995

👋 Introduction

Positioning:

The Mitsubishi Diamante (and its Japanese counterpart, the Sigma) was positioned as a premium, large front-wheel-drive sedan, competing in the luxury sedan segment against established Japanese and American rivals.

Competitors:

Key competitors included the Toyota Avalon, Lexus ES series, Nissan Maxima, and certain models from Acura and Cadillac during its production run.

Features:

Known for its comfortable ride, spacious interior, powerful V6 engines, and often feature-rich equipment levels for its time. Offered advanced technologies like multi-link suspension and electronically controlled transmissions.

📋 Manual Details

Primary Coverage:

Comprehensive factory service and repair

Estimated Pages:

1500+

Type:

Factory Service Manual

Language:

English

Format:

Printed (likely a compilation of factory bulletins)

📖 Manual Coverage

Engine Mechanical:

Engine assembly, disassembly, diagnostics, specifications, overhaul procedures for V6 engines.

Engine Electrical:

Ignition system, starting system, charging system, engine control unit (ECU), sensors, actuators, wiring diagrams.

Emission Control:

Exhaust gas recirculation (EGR), catalytic converter, evaporative emission control (EVAP), onboard diagnostics (OBD-I) and related components.

Fuel System:

Fuel injection system (MPI), fuel pump, fuel injectors, fuel pressure regulator, fuel tank, evaporative emissions.

Clutch:

Manual transmission clutch assembly, hydraulic system, service and adjustment procedures.

Transaxle Transmission:

Automatic transaxle (FWD) service, diagnostics, torque converter, valve body, internal components, fluid specifications and procedures. Manual transmission service.

Drive Shaft Axle:

Front and rear drive shafts, CV joints, axles, wheel bearings, service and replacement procedures.

Suspension:

Front and rear suspension systems (e.g., MacPherson struts, multi-link), shock absorbers, springs, control arms, bushings, alignment specifications.

Steering System:

Power steering system, steering rack, pump, hoses, tie rods, steering column, alignment, service and diagnosis.

Restraints:

Seat belts, airbag system (SRS) components, diagnostics, and safety precautions during servicing.

Brake System:

Front and rear disc brakes, ABS (Anti-lock Braking System) components, hydraulic lines, master cylinder, brake fluid specifications, bleeding procedures, diagnostics.

Body Interior Exterior:

Body panel removal and installation, interior trim, seats, dashboard, doors, windows, locks, seals, body repair guidelines.

Body Electrical System:

Lighting systems (headlights, taillights, interior), power windows, power locks, mirrors, audio system wiring, instrument cluster, body control modules, fused circuits.

Air Conditioning Heating:

HVAC system components, refrigerant handling, compressor, evaporator, condenser, heater core, blower motor, climate control system diagnostics and service.

Electrical Troubleshooting:

Systematic diagnostic procedures, wiring diagrams, component testing, common electrical faults and their resolutions.

Maintenance:

Oil changes, filter replacements, fluid checks and top-offs, spark plug replacement, belt inspection and replacement, brake pad/rotor service, tire rotation.

Diagnostics:

Component testing, fault code retrieval (OBD-I), symptom-based troubleshooting, electrical circuit testing, pressure testing.

Repair Overhaul:

Engine rebuild, transmission overhaul, suspension component replacement, brake system repair, steering system repair, body panel replacement, interior component repair.

Installation Replacement:

Component replacement for all major systems, including engine, transmission, suspension, brakes, electrical components, body parts.

Depth:

Comprehensive; covers everything from routine maintenance to complete vehicle overhaul and advanced electrical diagnostics.

📊 Manual Specifications

Format Details:

Likely a printed manual, potentially a compilation of official factory service bulletins and workshop manuals. If digital, expect a high-resolution PDF.

Quality:

Typically good to excellent for factory manuals, with clear diagrams and text.

Binding:

Professional binding (e.g., perfect bound, spiral bound, or binder format for factory originals).

Paper:

Durable paper stock, often with a glossy finish for diagrams and schematics.

⚙️ Engine Specifications

Engine Code And Type:

6G7x series V6 engines. Commonly 6G72 (3.0L SOHC/DOHC) and 6G73 (2.5L DOHC MIVEC - primarily Japan market Sigma).

3.0L V6 (6G72) Estimated Hp:

Approximately 170-200 hp (depending on DOHC/SOHC and market).

3.0L V6 (6G72) Estimated Torque:

Approximately 175-190 lb-ft (depending on DOHC/SOHC and market).

Injection Type:

Multi-Point Fuel Injection (MPI).

🔧 Transmission

Transmission Type:

Front-wheel drive (FWD) platform.

Transmission Options:

Primarily a 4-speed automatic transmission (e.g., F4A51). Manual transmission availability varied by market and trim.

Automatic Features:

Electronically controlled, with potential for 'Sport' or 'Economy' modes in some higher trims.

📐 Dimensions

Length Approx:

193-195 inches

Width Approx:

70.5 inches

Height Approx:

55-56 inches

Curb Weight Approx:

3500-3800 lbs

🛡️ Safety Features

NHTSA Ratings Early:

NHTSA and IIHS testing data for this era is less standardized than today, but the Diamante was designed to meet federal safety standards of the time. Specific ratings for the 1991-1995 models are not widely published in modern databases.

Active Safety:

Anti-lock Braking System (ABS) was typically available or standard on higher trims. Traction control was rare for this period.

Passive Safety:

Driver and front passenger airbags, three-point seat belts with pre-tensioners, reinforced body structure.

💡 Technology Features

Audio System:

Factory cassette player with AM/FM radio. CD player became optional/available on later models. Amplified sound systems were common on higher trims.

Driver Aids:

ABS was the primary driver assistance feature. Features like adaptive cruise control or lane keeping assist were not available.

Connectivity Features:

Limited to basic audio system connectivity. No Bluetooth or USB connectivity typical of modern vehicles.

🔧 Maintenance

Oil Change Interval:

Typically 3,000-5,000 miles or 3-6 months, depending on driving conditions and oil used. Consult the specific manual for exact recommendations.

Transmission Fluid Interval:

Recommended change every 30,000-60,000 miles, with filter replacement at the same time for automatic transmissions.

Timing Belt Interval:

Crucial for the V6 engines. Recommended replacement every 60,000 miles or 5 years due to potential interference engine design. Check the manual for specific engine code.

Engine Oil Type:

API SG or SH, SAE 5W-30 or 10W-30 (depending on climate). Consult manual for precise specification.

Transmission Fluid Type Auto:

Diamond ATF-SP II M (or equivalent DEXRON III/MERCON compatible fluid). Always verify with the manual.

Coolant Type:

Ethylene glycol based coolant, typically a 50/50 mix with distilled water. Green in color for this era.

Brake Fluid Type:

DOT 3 or DOT 4 (refer to manual for exact specification and reservoir cap).

Common Problems:

Timing belt failure (if not replaced on schedule), transmission solenoid issues, valve cover gasket leaks, ABS sensor failures, and typical aging electrical components (window motors, switches).

📚 Vehicle History

Mitsubishi History Notes:

Mitsubishi Motors, part of the vast Mitsubishi keiretsu, has a long history in automotive manufacturing, known for innovative technologies and robust engineering, particularly in its powertrain and 4WD systems (though Diamante is FWD).

Diamante Generation:

This covers the first generation of the Mitsubishi Diamante (JDM: Sigma) globally. It was based on the Mitsubishi Diamante/Sigma platform.

Production Years:

1990-1996 (Globally for the first generation). Sales in North America began in 1992.

Manufacturing Location:

Primarily Japan.

🏆 Awards & Recognition

Car And Driver Award Notes:

The Diamante/Sigma platform was recognized in Japan and sometimes internationally for its engineering and comfort, although specific awards like 'Car of the Year' might not have been prominent in the US market compared to its luxury segment competitors.