Vehicle Segment:
Luxury Grand Tourer (GT)
Target Audience:
Affluent buyers seeking performance, comfort, and advanced engineering
Key Competitors:
Ferrari 400 GT, Maserati Quattroporte, Jaguar XJ-S, Mercedes-Benz SEC Coupe
Unique Selling Proposition:
Front-engine, rear-wheel-drive V8 configuration with a transaxle for optimal weight distribution, advanced technology for its era
Manual Value Proposition:
Empowers owners and technicians to efficiently diagnose and repair complex electrical issues, saving significant labor costs.
Primary Focus:
Electrical System Troubleshooting and Repair
Secondary Focus:
Wiring Diagrams, Component Identification, Electrical Component Functionality
Estimated Pages:
100-250 (typical for a comprehensive wiring diagram manual of this era and complexity)
Type:
Wiring Diagram Manual / Electrical Troubleshooting Manual
Format:
Likely Print or High-Quality Scan PDF
Powertrain Electrical:
Engine Control Unit (ECU) wiring, Fuel Injection system, Ignition system, Starter system, Alternator system
Chassis Electrical:
Lighting (headlights, taillights, interior), Horn, Wipers and Washers, Power Mirrors, Power Antenna
Comfort Convenience:
Climate Control (HVAC), Power Seats, Power Windows, Central Locking System, Power Sunroof (if applicable), Cruise Control
Instrumentation Gauges:
Speedometer, Tachometer, Fuel Gauge, Oil Pressure Gauge, Temperature Gauge, Warning Lights
Audio Entertainment:
Factory Radio/Cassette Player wiring, Speaker wiring (may be basic)
Safety Features:
ABS (Anti-lock Braking System) wiring, Airbag system wiring (if applicable to Model 90)
Troubleshooting:
Step-by-step electrical fault diagnosis based on symptoms, logic charts, and component testing
Repair:
Guidance on replacing faulty electrical components, repairing wiring harness damage, and connector pin-outs
Component Testing:
Resistance, voltage, and continuity testing procedures for various electrical components
Wiring Harness Repair:
Techniques for identifying and repairing breaks, shorts, and corrosion within wiring harnesses
Depth:
Advanced Electrical Diagnostics, Component-Level Troubleshooting, System Schematics
User Level:
Suitable for experienced DIY enthusiasts and professional automotive technicians with basic electrical knowledge
Digital Format:
Likely PDF (searchable text and high-resolution diagrams)
Diagram Clarity:
High resolution for clear identification of wires, connectors, and components
Physical Binding:
If printed: Spiral-bound or saddle-stitched for lay-flat usability
Physical Paper:
If printed: Heavy-duty, glossy paper stock to withstand workshop environments
Displacement:
4.7 Liters (for early 'S' models), 5.0 Liters (for later 'S' models, including Model 90)
Bore X Stroke:
Refer to specific engine code documentation for precise measurements.
Horsepower Approx:
Approx. 306 hp (225 kW) for 4.7L, Approx. 292 hp (215 kW) for 5.0L (DIN ratings)
Torque Approx:
Approx. 290 lb-ft (393 Nm) for 4.7L, Approx. 305 lb-ft (414 Nm) for 5.0L
Injection Type:
Bosch L-Jetronic or Motronic fuel injection
Fuel Type:
Premium Unleaded Gasoline
ECU Type:
Bosch Motronic (specific model dependent)
Type:
4-Speed Automatic (Tiptronic introduced later, but typically not on 'Model 90')
Type:
5-Speed Manual (less common, often in earlier or European models)
Transaxle Layout:
Rear-mounted transaxle for 50/50 weight distribution
Transmission Fluid Type Placeholder:
Refer to manual for specific approved ATF (e.g., Dexron II or equivalent)
Crash Test Data:
Data specific to Model 90 may be limited; consult NHTSA or equivalent for general 928 data.
ABS:
Standard on 'S' models, with specific wiring and control module coverage
Traction Control:
Optional or standard on later models, check specific year features
Airbags:
Driver-side airbag typically standard on Model 90; passenger airbag optional or not present on earlier Model 90 variants.
Seatbelts:
Three-point seatbelts with pretensioners
Audio System:
Typically a high-quality factory cassette/radio system. Wiring diagrams will cover power, speakers, and antenna functions.
Cruise Control:
Integrated cruise control system with associated electrical controls and actuators.
Early Automation:
Features like power windows, locks, seats, and sunroof represent early forms of automotive automation with dedicated wiring.
Oil Change Interval:
Typically every 7,500-10,000 miles (12,000-16,000 km) or annually, whichever comes first.
Major Service Interval:
Timing belt replacement every 30,000-50,000 miles (48,000-80,000 km) or as specified by Porsche. Electrical system checks recommended annually.
Engine Oil Type Placeholder:
Refer to manual for specific viscosity (e.g., 15W-50 or 20W-50) and API classification.
Coolant Type:
Ethylene glycol-based coolant with corrosion inhibitors (Porsche recommended mix).
Brake Fluid Type:
DOT 4 or DOT 5.1 recommended, check manual for specific Porsche approval.
Electrical Gremlins:
Common issues include aging wiring insulation, failing relays, corroded ground points, and intermittent issues with comfort electronics. The manual is crucial for these.
Fuel System Components:
Fuel pump, injectors, and associated wiring can be points of failure.
Cooling System Electrical:
Fan motors, thermoswitches, and relays are critical electrical components that require regular inspection.
Introduction Year:
1978 (for original 928)
S Model Introduction:
1980 (928 S)
Model 90 Era:
Represents a late-stage development of the 928 S series, circa 1987-1991 model years, often featuring 5.0L engine and updated electronics.
Production Span:
1978-1995 (for the 928 range)
Manufacturing Location:
Stuttgart-Zuffenhausen, Germany
