Hi
Some books that could help in car diagnostics,
encyclopedia of electrical and electronic components,
Encyclopedia of Electronic Circuits
(Charles Platt) Encyclopedia of electrical and electronic components 1-3 vol.
(Tom Denton) Automobile Electrical and Electronic Systems:Vehicle Maintenance and Repair
(Tracy Martin) How to diagnose and repair automotive electrical systems
(Graf) Encyclopedia_of_Electronic_Circuits 1-6 vol.