The Mitsubishi Sigma, produced from 1990 to 1995, represents a sophisticated mid-size luxury sedan that competed in a segment often dominated by established Japanese and European marques. Sharing its platform with the Mitsubishi Diamante, the Sigma offered a compelling blend of refined styling, potent V6 engine options, and advanced technology for its time. Its engineering quality and reliability were hallmarks of premium offerings, aiming to provide a comfortable yet engaging driving experience. Notable features included advanced climate control, optional all-wheel drive, and a focus on driving dynamics, positioning it as a capable and luxurious choice for discerning drivers.
This factory service repair manual provides comprehensive guidance for the Mitsubishi Sigma, covering global markets with a specific emphasis on Japanese Domestic Market (JDM) specifications and tuning. It serves as an essential resource for owners, mechanics, and technicians, detailing everything from routine maintenance and periodic lubrication to complex troubleshooting and step-by-step repair procedures. The manual delves into all major systems, including the powertrain, chassis, suspension, brakes, steering, and electrical systems, alongside interior components and restraint systems. With its in-depth coverage, this manual ensures that the vehicle's performance, safety, and longevity can be effectively maintained and restored.
Years:
1990, 1991, 1992, 1993, 1994, 1995
Platform:
Mitsubishi Diamante (shared platform, Sigma was the JDM designation)
Chassis Codes:
Considered to be related to the JDM 'Sigma' which was based on the Mitsubishi Debonair platform, and the international Diamante.
Segment:
Mid-size luxury sedan (JDM), often considered a more upscale, performance-oriented sibling to mainstream Mitsubishi models of the era. Competed with Japanese luxury sedans and some European offerings.
Competitors:
Toyota Crown, Nissan Cedric/Gloria, Honda Legend, Mazda Luce, and potentially entry-level luxury sedans from European manufacturers.
Highlights:
Sophisticated styling, powerful V6 engines, advanced technology for its time, comfortable interior, and a focus on driving dynamics, especially in higher trims.
Regions Covered:
Global markets where the Mitsubishi Sigma or its international counterpart, the Diamante, was sold. Specific emphasis on Japanese Domestic Market (JDM) tuning and specifications.
Estimated Pages:
Hundreds (specific number not provided, but implied to be comprehensive)
Type:
Factory Service Repair Manual
Powertrain:
Engine Service/Repair, Transmission Service/Repair, Fuel Injection/Fuel System, Cooling System, Emission System, Engine Control System, Differential/Drive, Axle
Chassis And Suspension:
Brake System, Suspension, Steering, Chassis/Body
Electrical And Comfort:
Wiring Diagram, Electrical System, Heater/Air Conditioner, Interior, Restraint System
Maintenance:
General Maintenance, Periodic Lubrication
Diagnostics And Repair:
Troubleshooting, Step-by-step repair procedures, Diagnostic guides, Component testing and adjustment
Depth:
Comprehensive, covering everything from basic maintenance to complete rebuilds, intended for both professional technicians and knowledgeable owners.
Printability:
Fully printable, with individual pages or the entire manual selectable for printing. High resolution.
Binding:
N/A (Digital download, user printable)
Paper Type:
N/A (Digital download, user printable on desired paper type)
Engine Options:
Likely included Mitsubishi's 6G7x V6 engine family. Common displacements for this era include 3.0L (6G72) and potentially 2.5L (6G71) or 3.5L (6G73 or 6G74) depending on specific trim and market. The JDM Sigma was closely related to the Debonair, which featured V6 engines.
Horsepower Range:
Estimated 160-220+ hp depending on engine variant and forced induction (if applicable in certain trims).
Fuel Delivery:
Electronic Fuel Injection (EFI) across all engine variants.
Transmission Type:
Likely a 4-speed or 5-speed automatic transmission was standard or widely available. Manual transmissions may have been optional on certain sportier trims.
Transmission Options:
5-speed manual transmission (less common, especially in higher luxury trims).
AWD:
All-wheel drive (AWD) was available on some Diamante/Sigma models, often referred to as 'Viscous Coupling AWD' or similar systems.
Body Styles:
Primarily a four-door sedan. Convertible or coupe variants might have existed in limited production or aftermarket.
Seating Capacity:
Typically seating for 5 passengers.
Curb Weight Range:
Approx. 3,200 - 3,600 lbs (1450 - 1630 kg), varying with engine and drivetrain.
Crash Test Results:
Likely performed basic safety standards for the era. Specific ratings from NHTSA or IIHS might be difficult to find for JDM-specific models, but international Diamante testing can offer insights. Expect dual front airbags and potentially ABS as standard or optional on higher trims.
Active Safety:
Anti-lock Braking System (ABS) was likely available or standard on higher trims. Traction control may have been an option.
Passive Safety:
Frontal airbags for driver and passenger, crumple zones, side impact protection.
Audio System:
Factory-fitted radio/cassette player, often with premium speaker options. CD players became more common in later years. Limited digital integration compared to modern vehicles.
Advanced Features:
Electronic climate control, cruise control, power seats with memory (on some trims), keyless entry (late models).
Connectivity Options:
Minimal by today's standards. Primarily basic audio connectivity. No Bluetooth or USB integration from the factory.
Oil Change Interval:
Typically every 5,000 - 7,500 miles (8,000 - 12,000 km) or 6-12 months, depending on driving conditions and oil type used. Refer to manual for specific recommendations.
Engine Oil Viscosity:
Commonly 5W-30 or 10W-30 for gasoline engines, though specific recommendations may vary by engine and climate. Consult manual for precise API/ILSAC ratings.
Coolant Type:
Ethylene glycol-based coolant, typically a 50/50 mix with distilled water. Mitsubishi's proprietary DiaQueen Super Long Life Coolant (SLLC) or equivalent is recommended for optimal performance and longevity.
Transmission Fluid Type:
ATF SP-II or SP-III for automatic transmissions. Manual transmission fluid would be GL-4 or GL-5 rated gear oil.
Common Problems:
Valve stem seals leading to oil consumption, potential for radiator leaks, aging electrical components (e.g., sensors, relays), transmission control unit issues on some models, timing belt replacement is critical at specified intervals (often 60,000-90,000 miles/96,000-144,000 km).
Heritage Connection:
The Sigma was part of Mitsubishi's effort to compete in the premium and performance segments, building on the reputation of models like the Galant VR-4 and the luxury of the Debonair.
Generation:
The Sigma nameplate was used for Mitsubishi's premium large sedan in Japan, closely related to the international Mitsubishi Diamante. This generation aligns with the JDM Debonair's platform.
Manufacturing Locations:
Primarily manufactured in Japan by Mitsubishi Motors.
Industry Awards:
Specific awards for the Mitsubishi Sigma are not widely documented in English-language automotive press. However, the related Mitsubishi Diamante received positive reviews for its styling and technology from automotive journalists of the era.
