🏷️ Basic Information

Make:

BMW

Model:

850i

Chassis Code:

E31

Production Years:

1989-1999

Specific Model Years Covered:

1991-1992

Engine Code Indicator:

M70

Chassis Code Indicator:

E31

👋 Introduction

Vehicle Class:

Luxury Grand Tourer (GT), Personal Luxury Coupe.

Target Audience:

Affluent individuals seeking a high-performance, luxurious, and technologically advanced vehicle.

Key Competitors:

Mercedes-Benz SL-Class (R129), Porsche 928, Jaguar XJ-S.

Design Philosophy:

Elegant, timeless design with a focus on aerodynamics and driver comfort. A departure from BMW's traditional sporting sedans.

Powertrain Emphasis:

Powerful V12 engine providing smooth, effortless acceleration suitable for long-distance touring.

Purpose For Owner:

Empowers owners and independent technicians to diagnose and repair complex electrical issues efficiently, reducing reliance on dealership service.

📋 Manual Details

Primary Focus:

Electrical Systems Troubleshooting

Included Systems:

Power Distribution, Fuses, Grounds, Data Link, Engine Control, Charging, Starting, Transmission Control, SRS, ABS, Power Mirrors, Central Locking, Power Windows, Power Seats, Heated Seats, Sunroof, Horn, Wiper/Washer, Headlight Washer, Instrument Cluster, Clock, Lighting, Crash Control, Climate Control, Audio Systems, Telephone, Cruise Control, Anti-Theft, On-Board Computer

Estimated Pages:

Varies by edition, typically 300-600 pages for comprehensive electrical troubleshooting manuals.

Type:

Electrical Troubleshooting Manual / Wiring Diagram Manual

Language:

English (assumed based on product name, OEM manuals may also exist in German and other languages)

Format:

Digital (PDF) or Printed (likely intended for digital sale)

📖 Manual Coverage

Power Management:

Detailed charts and explanations for power distribution and fuse layouts.

Engine And Powertrain Electronics:

Engine Control System (DME), Electronic Transmission Control (EGS), Charging System, Starting System.

Chassis And Safety Electronics:

Slip Control ABS (Anti-lock Braking System), Supplemental Restraint System (SRS/Airbag), Crash Control Module.

Comfort And Convenience Electronics:

Power Mirrors, Central Locking, Power Windows, Power Seats, Heated Seats, Power Sun Roof, Horn, Wiper/Washer Systems, Headlight Washer, Windshield Washer Jet Heaters.

Instrumentation And Information:

Instrument Cluster, Multi-Function Clock, On-Board Computer.

Lighting Systems:

Light Switch Details, Headlights/Fog Lights, Turn/Hazard Lights, Park/Tail/Underhood Lights, License Plate/Luggage Compartment Lights, Back-up Lights, Brake Lights, Interior Lights, Glove Box/Ashtray Lights, Charging Socket.

Climate Control And Audio:

Park Ventilation with HKR (Heated Seats/Rear Window Defogger), Rear Window Defogger, Integrated Climate Regulation, Radio/CD Player, Radio/Hi-Fi, Cellular Telephone.

Driver Aids And Security:

Cruise Control (Tempomat), Anti-Theft System.

Troubleshooting Methodology:

Step-by-step diagnostic procedures for electrical faults, circuit analysis.

Component Identification:

Component Location Charts and Views to identify module and connector positions.

Wiring Diagrams:

Detailed wiring schematics for all covered electrical systems, including connector views and splice locations.

Fuse And Relay Identification:

Specific fuse and relay assignments with corresponding circuit functions.

Data Link Diagnosis:

Information related to accessing vehicle diagnostic data via the Data Link connector.

Depth:

Advanced diagnostic and troubleshooting, focusing on electrical fault finding and repair. Assumes a foundational understanding of automotive electrical principles.

📊 Manual Specifications

Digital Format:

PDF (Searchable text, vector graphics for diagrams highly desirable)

Diagram Clarity:

High-resolution diagrams essential for accurate interpretation of wiring and component layouts.

Physical Manual Binding:

If printed: Spiral-bound or perfect-bound for ease of use on a workbench.

Physical Manual Paper:

If printed: Durable, matte finish paper suitable for workshop environments.

⚙️ Engine Specifications

Engine Type:

Naturally Aspirated V12

Engine Code:

M70 B50

Displacement:

4.988 cc (5.0 Liters)

Horsepower:

296 hp @ 5,200 rpm

Torque:

317 lb-ft (430 Nm) @ 3,900 rpm

Fuel Delivery:

Bosch Motronic M-1.2 Electronic Fuel Injection (Dual ECUs, one per cylinder bank)

Fuel Type:

Premium Unleaded Gasoline (91 Octane or higher)

Cooling System:

Pressurized Liquid Cooling System

Ignition System:

Distributorless Ignition (Coil-on-plug per cylinder bank)

🔧 Transmission

Transmission Type:

4-speed Automatic (ZF 4HP24)

Manual Transmission Availability:

Optional 6-speed manual transmission (Getrag 420G) was available on some E31 models, but less common for the 850i and potentially not for the 91-92 E31 850i depending on market. This manual likely covers the automatic.

Electronic Control:

Electronic Transmission Control (EGS) for adaptive shifting and diagnostics.

Transmission Fluid Type:

BMW ATF LT-2 or equivalent (e.g., Pentosin ATF1100)

📐 Dimensions

Length:

Approx. 191.1 inches (4854 mm)

Width:

Approx. 71.7 inches (1821 mm)

Height:

Approx. 52.0 inches (1321 mm)

Wheelbase:

Approx. 106.3 inches (2700 mm)

Curb Weight:

Approx. 4,000-4,200 lbs (1814-1905 kg)

🛡️ Safety Features

Crash Test Data:

Limited official crash test data available from the period. Focus was on passive safety features.

Traction Control:

Automatic Stability Control (ASC) was available as an option on later models, ABS standard.

Braking System:

Anti-lock Braking System (ABS) standard.

Airbags:

Driver's side airbag standard.

Body Structure:

Reinforced safety cage, crumple zones.

💡 Technology Features

Audio System:

Optional high-fidelity audio systems, including BMW HiFi and potentially Harman Kardon (HKR).

Cd Player:

Factory fitted CD player or changer options were available.

Cruise Control:

Electronic cruise control (Tempomat) with steering wheel controls.

Cellular Telephone:

Integrated cellular telephone system with hands-free operation, a high-tech feature for its era.

Climate Control:

Dual-zone automatic climate control (Integrated Automatic Climate Control) with cabin air filtration.

Seat Features:

Power-adjustable front seats with memory functions, heated seats.

Anti Theft System:

Factory alarm system with central locking and immobilizer functions.

🔧 Maintenance

Oil Change Interval:

Recommended every 7,500-10,000 miles or annually, depending on usage and oil quality. Check owner's manual or specific service bulletin.

Major Service Intervals:

Spark plug replacement typically around 60,000 miles for V12. Inspect cooling system and belts every 30,000 miles.

Engine Oil Type:

BMW High Performance Synthetic Oil SAE 5W-30 or 10W-40 (refer to manual for specific viscosity recommendation based on climate).

Coolant Type:

BMW Blue Antifreeze/Coolant or equivalent (Ethylene Glycol based).

Brake Fluid Type:

DOT 4

Electrical Gremlins:

Common issues include failing door locks, window regulators, ABS sensors, headlight leveling systems, and intermittent dashboard warnings due to aging wiring and components.

Cooling System Issues:

Plastic coolant pipes and expansion tanks can become brittle and leak. Overheating is a significant concern if not maintained.

V12 Engine Maintenance:

Complex maintenance requiring specialized knowledge. Two separate engine management systems (DME) and exhaust systems contribute to complexity.

Suspected Fault Codes:

This manual will be invaluable for diagnosing codes related to DME, EGS, ABS, SRS, and various body control modules.

📚 Vehicle History

Bmw Brand Essence:

Renowned for performance, engineering excellence, and driver-focused vehicles ('The Ultimate Driving Machine').

E31 Development:

Conceived as a flagship luxury coupe, showcasing BMW's engineering prowess and design language for the 1990s. It was a significant departure from previous BMW coupes.

Variations:

Initially launched as the 850i with the V12 engine. Later versions included the 840Ci with a V8 engine and the M8 prototype. The 850CSi (S70 V12) was a high-performance variant.

Manufacturing Location:

Dingolfing, Germany

Production Volume E31:

Total E31 production was around 30,621 units across all variants.

Production Dates Covered:

July 1991 to August 1992, capturing early production runs of the V12 model.

🏆 Awards & Recognition

Design Awards:

While specific awards for the 1991-1992 models are not as prominently documented as later generations or M models, the E31's design was widely lauded for its elegance and timeless appeal, often cited in automotive design critiques.

Automotive Press Reviews:

Contemporary reviews praised its smooth V12 power, luxurious interior, and refined ride, positioning it as a true grand tourer.