Below is a list of useful resources with Maintenance Manuals, Technical Information and more for various makes and models.

General

charm.li / Service Manuals for Everyone
fusesdiagram.com / fuses locations and diagrams (all cars)
fuse-box.info / fuses locations and diagrams (all cars)
dtcdecode.com / DTCs Decode
nemigaparts.com / parts catalog, all makes
pinoutguide.com / pinouts (diagnostic connectors, radios, etc)
bosch-automotive-catalog.com / BOSCH parts catalog
webautocats.com / parts catalog, all makes
ilcats.ru / parts catalog, all makes
workshop-manuals.com / Free Online Workshop Repair Manuals
automotive-manuals.net / Free Online Workshop Repair Manuals
fccid.io / Database of wireless devices by FCC ID

Audi

nemigaparts.com/audi / Audi parts catalog ETKA

BMW

newtis.info / BMW Technical Information System TIS
bimmer-service / BMW and MINI Technical Information
bmwfault.codes BMW & MINI DTC (trouble code) lookup.
bimmer-dtc BMW & MINI DTC (trouble code) lookup (in German).
bimmer.work / BMW & MINI VIN decoder.
mdecoder.com / BMW & MINI VIN decoder.
realoem.com / BMW parts catalog ETK
nemigaparts.com/bmw / BMW parts catalog ETK
nemigaparts.com/bmw_old / BMW parts catalog old ETK
nemigaparts.com/bmw_moto / BMW parts catalog motorcycles ETK
bmwusa.com/owners-manuals.html / BMW owner manuals

Ferrari

ferrparts.com/Ferrari / Ferrari parts catalog

Lamborghini

ferrparts.com/Lamborghini / Lamborghini parts catalog

Land Rover

cat.lrparts.ru / Land Rover parts catalog
new.lrcat.com / Land Rover parts catalog up to 2017
landroverpartscounter.com / Land Rover parts catalog

Maserati

ferrparts.com/Maserati / Maserati parts catalog

Mercedes

http://benz.ehost.tj / WebETM Starfinder (2016)
https://www.datamb.com / Mercedes VIN decoder with datacard.
mboemparts.com / Mercedes parts catalog EPC
nemigaparts.com/mercedes / Mercedes parts catalog EPC
mercedes-benz-publicarchive.com / Mercedes Public Archive
STAR Tekinfo / models 124 129 140 163 170 201 202 208 210 215 220

MINI

nemigaparts.com/mini / MINI parts catalog ETK
realoem.com / MINI parts catalog ETK

Porsche

nemigaparts.com/porsche / Porsche parts catalog PET
autoatlanta.com / Porsche parts catalog PET

SMART

nemigaparts.com/smart / SMART parts catalog EPC

Volkswagen

wiki.ross-tech.com / VAG technical resources
nemigaparts.com/volkswagen / Volkswagen parts catalog ETKA
parts.vw.com / Volksvagen parts catalog ETKA

Volvo