🏷️ Basic Information

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

Engine Code 840Ci:

M60B40 (4.0L V8)

Engine Code 850Ci:

M70B50 (5.0L V12)

Engine Code 850Csi:

S70B56 (5.6L V12)

👋 Introduction

Positioning:

Flagship luxury coupe and convertible offering performance, technology, and sophisticated design.

Competitors:

Mercedes-Benz SL-Class (R129), Porsche 911 (993), Jaguar XJS.

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

Years Covered:

1993-1994

Production Dates Covered:

September 1993 - May 1994

Regions Covered:

Global (based on technical content)

Estimated Page Count:

200-300 pages (typical for this type of manual)

Type:

Electrical Troubleshooting Manual / Service Manual

Language:

English

Format:

Likely PDF (digital) or printed booklet

📖 Manual Coverage

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.

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.

Depth:

Highly detailed, focusing on diagnostic procedures, circuit diagrams, and troubleshooting steps for specific electrical faults.

📊 Manual Specifications

Digital Format:

Searchable PDF with high-resolution diagrams

Print Quality:

Professional-grade printing with clear, legible schematics and text.

Binding:

Perfect bound or spiral bound for ease of use in a workshop environment (for printed versions).

Paper Type:

Durable, high-quality paper stock suitable for workshop use.

⚙️ Engine Specifications

Engine:

M60B40 4.0L V8

Horsepower 840Ci:

282 hp @ 5800 rpm

Torque 840Ci:

295 lb-ft @ 4500 rpm

Engine:

M70B50 5.0L V12

Horsepower 850Ci:

296 hp @ 5200 rpm

Torque 850Ci:

332 lb-ft @ 4100 rpm

Engine:

S70B56 5.6L V12 (Alpina-tuned)

Horsepower 850Csi:

375 hp @ 5300 rpm

Torque 850Csi:

406 lb-ft @ 4000 rpm

Injection Type:

Bosch Motronic Electronic Fuel Injection (EFI)

Spark Plugs:

Specialized spark plugs often required for V12 models; consult manual for specific part numbers and replacement intervals.

🔧 Transmission

Type:

5-speed automatic (Steptronic optional later)

Type:

6-speed manual (less common)

Type:

6-speed manual

Type:

4-speed automatic (less common)

Type:

6-speed manual (Getrag 420G)

Electronic Control:

Electronic transmission control for smooth gear changes and adaptive shift programs.

📐 Dimensions

Length:

Approx. 4,775 mm (188.0 in)

Width:

Approx. 1,855 mm (73.0 in)

Height:

Approx. 1,370 mm (53.9 in)

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

Crash Test Data:

Limited official data from era, but built to high safety standards for luxury vehicles.

ABS:

Anti-Slip Regulation (ASR) / Anti-lock Braking System (ABS) standard on most models.

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

Radio System:

Integrated radio/cassette player, often with an optional CD player and sophisticated Hi-Fi sound systems (e.g., Harman Kardon).

Cruise Control:

Standard cruise control (Tempomat) functionality.

Cellular Telephone:

Optional integrated cellular telephone system.

Instrument Cluster:

Comprehensive instrument cluster with tachometer, speedometer, fuel gauge, oil temperature, and warning indicators.

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

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.

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

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 wear or motor failure.

Engine Oil Leaks:

Common issues include oil pan gasket and valve cover gasket leaks.

📚 Vehicle History

Philosophy:

BMW's reputation for engineering excellence, driver engagement, and performance.

E31 Development:

Developed as BMW's halo car, showcasing advanced technology and design.

Production Years:

1989-1999

Manufacturing Location:

Dingolfing, Germany

Rarity:

The 850Csi, in particular, is a rare and highly sought-after model.

🏆 Awards & Recognition

Automotive Press:

Consistently praised by automotive journalists for its styling, performance, and luxury when new.

Consumer Reports:

While specific ratings vary, generally recognized as a well-engineered, albeit complex, luxury vehicle.