🏷️ Basic Information Identification Make: BMW Model: 840Ci / 850Ci / 850Csi Chassis Code: E31 Product Type: Electrical Troubleshooting Manual Product Name: BMW 840Ci 850Ci-Csi (E31) 1993-1994 Electrical TROUBLESHOOTI Codes Engine Code 840Ci: M60B40 (4.0L V8) Engine Code 850Ci: M70B50 (5.0L V12) Engine Code 850Csi: S70B56 (5.6L V12) 👋 Introduction Market Position Positioning: Flagship luxury coupe and convertible offering performance, technology, and sophisticated design. Competitive Analysis Competitors: Mercedes-Benz SL-Class (R129), Porsche 911 (993), Jaguar XJS. Key Features Design Philosophy: Long, elegant lines, shark-nose front fascia, and frameless windows, embodying BMW's 'ultimate driving machine' ethos in a grand tourer format. Electrical Complexity: Advanced for its era, with a sophisticated network of electronic control units (ECUs) managing various vehicle functions. 📋 Manual Details Coverage Areas Years Covered: 1993-1994 Production Dates Covered: September 1993 - May 1994 Regions Covered: Global (based on technical content) Page Count Estimated Page Count: 200-300 pages (typical for this type of manual) Manual Type Type: Electrical Troubleshooting Manual / Service Manual Language Language: English Format Format: Likely PDF (digital) or printed booklet 📖 Manual Coverage Systems Covered Electrical Systems: All E31 electrical systems, including power distribution, fuses, grounds, data link, engine control, charging, starting, transmission control, SRS, ABS, power accessories, lighting, interior, climate control, infotainment, cruise control, and anti-theft. Procedures Included Troubleshooting Procedures: Diagnostic flowcharts, symptom-based troubleshooting, electrical schematic interpretation, component testing, and fault code diagnosis. Component Location: Detailed diagrams showing the location of electrical components, modules, and connectors within the vehicle. Technical Depth Depth: Highly detailed, focusing on diagnostic procedures, circuit diagrams, and troubleshooting steps for specific electrical faults. 📊 Manual Specifications File Format Digital Format: Searchable PDF with high-resolution diagrams Print Quality Print Quality: Professional-grade printing with clear, legible schematics and text. Binding Type Binding: Perfect bound or spiral bound for ease of use in a workshop environment (for printed versions). Paper Type Paper Type: Durable, high-quality paper stock suitable for workshop use. ⚙️ Engine Specifications Primary Engine 840Ci Engine: M60B40 4.0L V8 Horsepower 840Ci: 282 hp @ 5800 rpm Torque 840Ci: 295 lb-ft @ 4500 rpm Primary Engine 850Ci Engine: M70B50 5.0L V12 Horsepower 850Ci: 296 hp @ 5200 rpm Torque 850Ci: 332 lb-ft @ 4100 rpm Primary Engine 850Csi Engine: S70B56 5.6L V12 (Alpina-tuned) Horsepower 850Csi: 375 hp @ 5300 rpm Torque 850Csi: 406 lb-ft @ 4000 rpm Fuel System Injection Type: Bosch Motronic Electronic Fuel Injection (EFI) Maintenance Notes Spark Plugs: Specialized spark plugs often required for V12 models; consult manual for specific part numbers and replacement intervals. 🔧 Transmission Standard 840Ci Type: 5-speed automatic (Steptronic optional later) Optional 840Ci Type: 6-speed manual (less common) Standard 850Ci Type: 6-speed manual Optional 850Ci Type: 4-speed automatic (less common) Standard 850Csi Type: 6-speed manual (Getrag 420G) Features Electronic Control: Electronic transmission control for smooth gear changes and adaptive shift programs. 📐 Dimensions Exterior Length: Approx. 4,775 mm (188.0 in) Width: Approx. 1,855 mm (73.0 in) Height: Approx. 1,370 mm (53.9 in) Weights Curb Weight 840Ci: Approx. 1,730 kg (3,814 lbs) Curb Weight 850Ci: Approx. 1,950 kg (4,300 lbs) Curb Weight 850Csi: Approx. 1,950 kg (4,300 lbs) 🛡️ Safety Features Ratings Crash Test Data: Limited official data from era, but built to high safety standards for luxury vehicles. Active Features ABS: Anti-Slip Regulation (ASR) / Anti-lock Braking System (ABS) standard on most models. Passive Features Airbags: Driver airbag standard, passenger airbag optional or standard on later models. Seatbelts: Pre-tensioned seatbelts. Srs: Supplemental Restraint System (SRS) for airbags. 💡 Technology Features Infotainment Radio System: Integrated radio/cassette player, often with an optional CD player and sophisticated Hi-Fi sound systems (e.g., Harman Kardon). Driver Assistance Cruise Control: Standard cruise control (Tempomat) functionality. Connectivity Cellular Telephone: Optional integrated cellular telephone system. Instrumentation Instrument Cluster: Comprehensive instrument cluster with tachometer, speedometer, fuel gauge, oil temperature, and warning indicators. Comfort Features Climate Control: Dual-zone automatic climate control (Integrated climate regulation). Heated Seats: Optional heated front seats. Power Seats: Electrically adjustable front seats with memory functions. 🔧 Maintenance Service Intervals Oil Change: Typically every 7,500-10,000 miles or 12 months (refer to specific model/year recommendations in the manual). Major Service: Major services often recommended around 30,000 and 60,000 miles, including spark plugs, filters, and inspection of key components. Fluid Specifications Engine Oil 840Ci: BMW Longlife-98 5W-30 or 5W-40 synthetic oil Engine Oil 850Ci/Csi: BMW Longlife-98 5W-30 or 5W-40 synthetic oil (check specific capacity for V12). Coolant: BMW Blue Coolant (G48) or equivalent ethylene glycol-based coolant Brake Fluid: DOT 4 brake fluid Known Issues Electrical Gremlins: Age-related deterioration of wiring insulation, connector corrosion, and sensor failures are common. This manual is crucial for diagnosing these. Srs System: SRS warning lights can be triggered by faulty seat occupancy sensors or clock springs. Heater Control Valve: Common failure point on climate control systems, leading to HVAC issues. Power Window Regulators: Can become slow or inoperable due to...