Target Audience:
Owners and independent mechanics of the 1991 BMW 850i E31 seeking to perform their own maintenance and repairs, particularly those focused on electrical systems.
Value Proposition:
Provides essential, detailed wiring information often missing or difficult to obtain in generic repair manuals, enabling a higher level of DIY repair capability.
Diy Empowerment:
Encourages and facilitates DIY repairs by offering clear, step-by-step diagrams and comprehensive system coverage.
Tool Acquisition Incentive:
Aligns with the idea of tool acquisition for DIY enthusiasts, enhancing the overall experience.
Systems Covered Overview:
Comprehensive coverage of all major vehicle systems, including electrical, powertrain, chassis, and body.
Specific Sections Mentioned:
Index, Introduction, Symbols, Power Distribution Chart, Fuse Chart, Power Distribution, Diagnostic Link, Injection Electronic, Charging System.
Estimated Page Count:
Detailed wiring diagrams suggest a substantial page count, likely exceeding 300 pages for complete coverage of all electrical systems.
Manual Type:
Service & Repair Manual (Wiring Diagram Focused)
Electrical Systems:
Extensive coverage of the entire electrical system, including power distribution, lighting, ignition, starting, charging, engine management, comfort systems, and instrumentation.
Engine Management:
Detailed wiring for the Motronic engine management system, including fuel injection, ignition timing, and sensor inputs.
Power Distribution:
Thorough diagrams illustrating power flow, including battery, alternator, starter, fuse boxes, and relay assignments.
Charging System:
Specific wiring for the alternator and voltage regulator circuits.
Starting System:
Wiring diagrams for the starter motor, ignition switch, and related relays/solenoids.
Lighting System:
Diagrams for headlights, taillights, interior lighting, and accessory lighting.
Instrumentation And Gauges:
Wiring for the instrument cluster, including speedometer, tachometer, fuel gauge, temperature gauge, and warning lights.
Comfort And Convenience:
Wiring for climate control, power windows, power seats, central locking, and other comfort features.
Fuse And Relay Information:
Detailed fuse charts and relay assignments, crucial for electrical troubleshooting.
Troubleshooting Guidance:
Provides the foundational wiring information necessary for diagnosing electrical faults and system failures.
Component Identification:
Diagrams clearly label wires, connectors, components, and their respective functions.
Diagnostic Link Information:
Details regarding the diagnostic connector and its pin assignments, facilitating the use of diagnostic tools.
Wire Color Codes:
Diagrams utilize standard wire color coding for easy identification.
Connector Pinouts:
Essential pinout data for various electrical connectors, aiding in testing and repair.
Wiring Complexity:
Detailed, multi-color wiring diagrams designed for complex automotive electrical systems.
Diagnostic Approach:
Empowers DIY mechanics with the visual information required for systematic troubleshooting of electrical issues.
Component Interconnectivity:
Illustrates how various electrical components and circuits interact, crucial for understanding system behavior.
Audio System:
Original BMW E31 audio systems often included cassette decks and premium sound options (e.g., HiFi system).
Cruise Control:
Electronic cruise control system.
Traction Control:
Automatic Stability Control (ASC) or Automatic Stability Control + Traction (ASC+T) systems were available.
Diagnostics:
On-board diagnostics accessed via a dedicated connector, supported by this manual.
Oil Change Interval:
Typically 10,000-15,000 miles or 12-24 months, consult owner's manual for specific recommendations.
Spark Plug Replacement:
Refer to manual; typically around 30,000-60,000 miles for iridium or platinum plugs.
Engine Oil Type:
BMW Longlife-98 specification, typically a 5W-30 or 5W-40 synthetic oil.
Engine Oil Capacity:
Approximately 7.5 liters (7.9 US quarts)
Coolant Type:
BMW Blue (G48) or equivalent ethylene glycol-based coolant.
Transmission Fluid Type:
ZF TE-ML 11A or equivalent ATF for 4HP24.
Cooling System:
Plastic coolant expansion tank can become brittle and crack over time, leading to leaks.
Electrical Connectors:
Degradation of wiring insulation and connectors, particularly in high-heat areas, can lead to intermittent electrical faults.
Ignition Coils:
M70 V12 engine uses 6 ignition coils; failure of one can affect performance. Often replaced in sets.
Power Steering System:
Leaks from power steering hoses or pump can occur.
