1990 Chevy Firewall Wiring Diagram. The first pic looks to definitely be to your coolant temp sending unit which should be right there in the head. Okay ill try my best here as i have been over the wiring on my 1989 which isnt much different than your 1990.
1988 chevrolet blazer 2dr suv wiring information. Index of wiring diagrams. Access our free wiring diagrams repair guide for gm full size trucks 1988 1998 through autozone rewards.
I also have the factory wiring diagrams which are way better than chilton.
1989 chevrolet astro van wiring information. As stated previous the traces in a 1990 chevy truck wiring diagram signifies wires. The older manuals didnt include wiring. 1990 chevrolet c1500 2dr ext cab pickup wiring information.