Target Audience:
Porsche 928 S Model 85 owners, independent workshops, automotive technicians
Value Proposition:
Enables cost-effective DIY diagnosis and repair of electrical issues, reducing workshop bills.
Alternative Resources:
Official Porsche workshop manuals (often expensive and difficult to obtain for older models), general automotive repair guides (less specific).
Focus:
Dedicated to the electrical system, providing detailed schematics often missing in general manuals.
Diagnostic Aid:
Empowers users with the technical information needed to accurately pinpoint electrical faults.
Understandability:
Designed to be understandable with basic electronic knowledge and the diagrams provided.
Primary Coverage:
Electrical System
Secondary Coverage:
Troubleshooting and Diagnosis
Estimated Page Count:
Likely 100-200 pages (typical for specialized wiring diagrams)
Type:
Wiring Diagram Manual / Electrical Troubleshooting Manual
Format:
Likely PDF (digital download), potentially printable
Engine Management Electrical:
Fuel Injection, Ignition, ECU Wiring
Lighting System:
Headlights, Taillights, Interior Lighting, Fog Lamps
Instrumentation:
Gauges, Warning Lights, Trip Computer
Power Accessories:
Power Windows, Power Locks, Power Seats, Sunroof
Climate Control:
HVAC Blower Motor, Climate Control Unit Wiring
Audio System:
Radio/Cassette Player Wiring, Speaker Connections
Wiper Washer System:
Wiper Motor, Washer Pump Wiring
Horn System:
Horn Circuitry
Starter Charging System:
Alternator, Starter Motor Relays
Safety Systems:
ABS (Anti-lock Braking System) Wiring (if applicable)
Troubleshooting Methodology:
Step-by-step diagnostic procedures for electrical faults
Component Testing:
Guidance on testing relays, switches, motors, and sensors
Wiring Harness Identification:
Clear identification of wire colors, gauge, and routing
Fuse Relay Locations:
Identification of fuse box and relay panel locations and functions
Connector Pinouts:
Detailed pin-out diagrams for various electrical connectors
Diagnostic Level:
Advanced diagnostics, suitable for professional technicians and advanced DIYers
Repair Level:
Detailed repair procedures for wiring harness issues, component replacement
Understanding Required:
Assumes basic understanding of automotive electrical principles and ability to read schematics
Engine Type:
V8, Naturally Aspirated
Displacement:
4.7 Liters (4664 cc)
Bore X Stroke:
94.0 mm x 84.0 mm
Compression Ratio:
10.0:1 (approximate)
Valve Train:
SOHC (Single Overhead Camshaft), 2 valves per cylinder
Horsepower:
250 PS (184 kW) at 5,500 rpm (DIN specification for US models)
Torque:
340 Nm (251 lb-ft) at 4,000 rpm (DIN specification for US models)
Fuel Delivery:
Bosch L-Jetronic Fuel Injection
Fuel Type:
Unleaded Premium Gasoline (91 Octane or higher recommended)
Crash Test Data:
Limited public data for this era, but Porsche vehicles are known for robust construction.
ABS:
Optional Anti-lock Braking System (ABS)
Brakes Front:
Ventilated Disc Brakes
Brakes Rear:
Ventilated Disc Brakes
Seat Belts:
Three-point inertia-reel seat belts with pre-tensioners
Steering Column:
Collapsible steering column
Body Structure:
Reinforced safety cage and crumple zones
Audio System:
Factory fitted AM/FM Cassette Radio with integrated amplifier (e.g., Blaupunkt Monterey).
Speaker Configuration:
Typically 4 or 6 speaker system.
ABS Availability:
Optional ABS system, its wiring and diagnostics are crucial and likely covered.
OBD Ii:
Not applicable. OBD-I diagnostics may be covered indirectly via specific component testing procedures.
Oil Change Interval:
Every 12,000 km or 12 months (whichever comes first)
Timing Belt Interval:
Every 80,000 km or 4 years (critical for V8 engine)
Brake Fluid Change:
Every 2 years
Engine Oil Type:
SAE 20W-50 or 15W-50 Synthetic (e.g., Mobil 1 15W-50, Castrol Syntec 20W-50)
Engine Oil Capacity:
Approx. 8.5 liters (with filter)
Coolant Type:
Porsche approved ethylene glycol based coolant (e.g., Porsche Part # 000 043 303 05)
Transmission Fluid Manual:
GL-5 Gear Oil, SAE 75W-90 (e.g., Mobil 1 75W-90)
Transmission Fluid Automatic:
Dexron III (or equivalent) ATF
Electrical Gremlins:
Common issues include aged wiring insulation, failing relays, and corrosion in connectors, particularly evident in the fuse box and engine bay harness. The manual directly addresses these.
Fuel System Issues:
While not electrical, fuel pump relay failures can cause no-start conditions. The manual will show its location and wiring.
Cruise Control Failures:
Vacuum leaks or electrical faults in the cruise control module/actuator can lead to malfunctions.
Brand Focus:
Porsche is renowned for its high-performance sports cars and engineering excellence.
928 Introduction:
The 928 was introduced as a successor to the legendary 911, designed to be a more comfortable and modern grand tourer.
928 S Variant:
The 'S' model represented an enhancement with a larger engine and improved performance over the original 928.
85 Update:
The 1985 model saw further refinements, including potential upgrades to the L-Jetronic system and chassis.
Production Years:
1977-1995 (across all variants)
Manufacturing Location:
Stuttgart, Germany
