The Porsche 928 S4-GT, a distinguished model from the third generation of the 928 lineage, represents Porsche's commitment to the grand touring segment. Produced between 1987 and 1991, this front-engine, rear-wheel-drive V8-powered coupe was engineered for comfortable high-speed travel, blending potent performance with refined luxury. Its iconic design, featuring aerodynamic lines and pop-up headlights, housed a sophisticated transaxle layout for optimal weight distribution and a powerful 32-valve V8 engine. The S4 and GT variants further refined this concept, offering enhanced power and driving dynamics, making it a unique competitor in the premium GT market.

This manual serves as a comprehensive guide focused on the Electrical System Diagnostics and Repair of the Porsche 928 S4-GT. It covers essential areas such as electrical component troubleshooting, wiring harness repair, and fuse and relay identification, providing detailed wiring diagrams. The scope includes power distribution, ignition and fuel systems, engine management, lighting, instrumentation, comfort controls, audio systems, braking, and chassis electronics. With step-by-step diagnostic procedures, repair instructions, and component testing guidance, this manual is an indispensable resource for owners and technicians aiming to maintain and restore the electrical integrity of this exceptional vehicle.