🏷️ Basic Information

Make:

BMW

Model:

850i

Chassis Code:

E31

Product Name:

BMW 850i (E31) 1992-1993 Electrical TROUBLESHOOTING Manual

Vehicle Production Dates:

July 1992 - August 1993

👋 Introduction

Positioning:

The BMW 850i (E31) represented the pinnacle of BMW's luxury grand tourer offerings in the early 1990s, targeting discerning buyers seeking performance, luxury, and advanced technology.

Competitors:

Competed with high-end luxury coupes from brands like Mercedes-Benz (e.g., S-Class Coupe), Jaguar, and Porsche.

Defining Features:

V12 engine, advanced aerodynamic design, sophisticated interior, and a suite of electronic features for its era, setting a benchmark for GT cars.

📋 Manual Details

Primary Focus:

Electrical Systems and Troubleshooting

Included Systems:

Power Distribution, Fuses, Grounds, Data Link, Engine Control, Charging, Starting, Electronic Transmission Control, SRS, ABS, Power Mirrors, Central Locking, Power Windows, Power Seats, Heated Seats, Power Sunroof, Horn, Wiper/Washer, Headlight Washers, Washer Jet Heaters, Instrument Cluster, Multi-Function Clock, Lighting Controls, Exterior Lighting (Headlights, Fog Lights, Turn/Hazard, Park/Tail/Underhood, License Plate/Luggage Compartment, Backup, Brake), Interior Lighting, Glove Box/Cassette/Ashtray Lights, Charging Socket, Crash Control Module, Park Ventilation with HKR, Rear Window Defogger, Climate Control, Radio/CD Player, Radio/Hi-Fi, Cellular Telephone, Cruise Control, Anti-Theft System, On-Board Computer

Estimated Page Count:

Estimated 400-600 pages (typical for comprehensive electrical troubleshooting)

Type:

Electrical Troubleshooting Manual

Language:

English

Format:

Digital (PDF) or Printed

📖 Manual Coverage

Breadth Of Coverage:

Comprehensive coverage of all major electrical and electronic systems specific to the E31 850i model produced within the specified timeframe.

Troubleshooting Methodology:

Detailed step-by-step troubleshooting procedures, diagnostic flowcharts, symptom-based diagnosis, component testing, wiring diagram interpretation, and diagnostic trouble code (DTC) explanations.

Depth:

Advanced diagnostic and repair procedures, including component-level troubleshooting, wiring harness analysis, connector views, splice locations, and power distribution analysis.

📊 Manual Specifications

Digital Format:

Searchable PDF with high-resolution diagrams and text.

Print Quality:

High-quality printing with clear, legible diagrams and text (for physical copies).

Binding:

Professional binding (e.g., perfect bound or spiral bound) for durability in a workshop environment (for physical copies).

Paper Quality:

Durable, high-quality paper stock suitable for workshop use (for physical copies).

⚙️ Engine Specifications

Engine Code:

M70

Engine Type:

60-degree V12

Displacement:

5.0 Liters (4988 cc)

Horsepower:

296 bhp @ 5200 rpm

Torque:

332 lb-ft @ 4100 rpm

Fuel Delivery:

Bosch Motronic M-1.2 Electronic Fuel Injection (EFI) with two ECUs (one per cylinder bank).

Ignition Type:

Distributorless Ignition System (DIS) with two ignition coils.

Coolant Type:

BMW Blue Antifreeze/Coolant (typically a 50/50 mix with distilled water). Consult manual for specific P/N.

🔧 Transmission

Transmission Type:

4-speed Automatic (ZF 4HP-24)

Optional Transmission:

6-speed Manual (Getrag 265/6 - very rare for 850i, more common on 850CSi and other models).

Automatic Transmission Features:

Electronic Transmission Control (ETC) with sport/economy modes.

Automatic Transmission Fluid:

Dexron III or equivalent. Consult manual for specific BMW part number (e.g., BMW ATF LT-2, 83 22 9 407 812).

📐 Dimensions

Length:

Approx. 192.4 inches (4887 mm)

Width:

Approx. 71.7 inches (1821 mm)

Height:

Approx. 51.6 inches (1311 mm)

Curb Weight:

Approx. 4350 - 4500 lbs (1973 - 2041 kg)

Gross Vehicle Weight Rating:

Not commonly specified as a rigid GVWR, but approximate load capacity should be considered.

🛡️ Safety Features

Crash Test Results:

Vehicle safety standards of the era. Specific government crash test ratings (e.g., NHTSA, Euro NCAP) may not be readily available or comparable to modern standards. Refer to historical automotive publications.

Active Safety Features:

Anti-lock Braking System (ABS) - Bosch ABS II, Automatic Stability Control (ASC) - available on some models.

Passive Safety Features:

Driver and passenger front airbags (Supplement Restraint System - SRS), front and rear crumple zones, reinforced safety cage.

Child Seat Anchors:

Not equipped with ISOFIX anchors. Older vehicles of this era typically used seat belts for child seat restraint.

💡 Technology Features

Audio System:

BMW Bavaria C Business/Professional CD, Hi-Fi sound system, optional Harman Kardon sound system.

Navigation:

Optional BMW navigation system (early generation, CD-ROM based).

Cruise Control:

Standard cruise control ('Tempomat') with electronic activation and speed regulation.

Telephone:

Optional integrated cellular telephone system with handset and external antenna.

On Board Computer:

BMW On-Board Computer (OBC) providing information on fuel consumption, range, average speed, and system diagnostics.

Climate Control:

Automatic climate control with dual-zone temperature settings and integrated climate regulation system.

Anti Theft System:

Factory-installed anti-theft alarm system with immobilizer.

🔧 Maintenance

Oil Change Interval:

Typically every 7,500-10,000 miles or 12-18 months, depending on driving conditions. Refer to specific service advisor recommendations based on onboard computer diagnostics.

Major Service Items:

Spark plug replacement (e.g., M70 requires 12 spark plugs), coolant flush, brake fluid flush, transmission fluid and filter change, differential fluid change.

Engine Oil Type:

SAE 0W-40 or 5W-40 synthetic oil meeting BMW Longlife-01 (LL-01) specifications is recommended for optimal performance and protection. Consult manual for exact specification and API rating.

Engine Oil Capacity:

Approx. 7.5 Liters (8.0 US Quarts) with filter change.

Coolant Capacity:

Approx. 10.5 Liters (11.1 US Quarts).

Brake Fluid Type:

DOT 4 (or BMW DOT 4 High Performance). Consult manual for specific BMW part number (e.g., 81 22 9 407 940).

Power Steering Fluid Type:

BMW Hydraulic Fluid (CHF 11S) or Pentosin CHF 11S. Consult manual for specific BMW part number (e.g., 81 22 9 407 784).

Common Electrical Issues:

Door handle microswitches, ABS/ASC sensor failures, headlight leveling system issues, central locking module problems, window regulator failures, corroded ground points, EML (Engine Load Management) faults, SRS warning lights.

Common Mechanical Issues:

V12 engine maintenance complexity, cooling system component degradation (hoses, water pump), fuel pump failures, catalytic converter issues, aging wiring harnesses, VANOS system issues (if applicable to specific E31 variants).

Spark Plug Part Number:

Refer to manual for specific part numbers. Typically NGK or Bosch platinum or iridium plugs, 12 required (e.g., NGK BKR6EQUP, Bosch FGR7KQE).

Tire Size:

Common sizes include 235/45R17 front and 255/40R17 rear. Consult vehicle placard or manual for exact specifications and approved tire types.

Wheel Bolt Pattern:

5x120mm

Wheel Offset:

Typically ET15 to ET22. Consult manual for specific OE wheel offsets.

📚 Vehicle History

Brand Focus:

BMW is renowned for its 'Ultimate Driving Machine' philosophy, emphasizing performance, engineering excellence, and luxury.

E31 Development:

The E31 was BMW's first modern V12-powered coupe, designed to compete in the premium luxury GT segment. It featured a distinctive, frameless window design and pop-up headlights.

Production Years:

1989-1999

Manufacturing Location:

Germany

🏆 Awards & Recognition

Automotive Press Awards:

While specific awards for the 1992-1993 models are not a primary focus of this manual, the E31 8 Series generally received praise for its design, V12 engine, and luxury touring capabilities from automotive journalists of its era.

Design Appreciation:

Considered a design icon of its time, with its sleek, aerodynamic profile and absence of B-pillars (in the traditional sense) due to the frameless door glass.