Primarily asking this question because of that new TV show "Revolution". I remember reading this novel back in the 80's about a mysterious monolith that renders all electronics in the world inoperable. The novel never explains where the monolith came from, only how civilization adjusted.
The date was Friday, the third of August. For some people the day was just beginning. For others it was the end of another perfectly normal day. Then right across the world every ground and airborne radar screen went haywire
This time it had really happened. An alien spacecraft was in orbit around planet Earth. And nine weeks later civilization was on the edge of a total breakdown more devastating than any nuclear war or natural disaster
This is a mildly unlikely match because the effect of the alien arrival is to disrupt all radio communication (thus the title, Fade-Out, referring to a radio communication concept) rather than to disable all electricity.
The premise of the show reminded me of Robert Silverberg's "The Alien Years". Although that novel is not about a monolith, but rather about an alien invasion.
Fifteen feet tall, the Entities land in cities across Earth. Ignoring humankind, they wall themselves in impenetrable enclaves, enslaving a few willing collaborators with their telepathic PUSH. Then they plunge humans into a new Dark Age without electricity, allowing us to live--but no longer as a dominant species.
But a few refuse to submit to fate, including the Carmichael family, whose patriarch, an aging colonel devoted to resistance, will inspire a daring new generation of dissidents. United in spirit, these diverse rebels--an aging hippie, a cold-blooded Muslim assassin, a prodigal son, and a renegade hacker--will carry on the colonel's legacy as they attempt to kill the mysterious Prime Entity and free the planet.
Your description reminds me of the classic French SF novel Ravage by René Barjavel. The story describes a future society in which all electrical devices have suddenly become inactive. The reason for the disappearance of electricity is not an important part of the book, I don't remember whether it's stated or left unsaid. The alien monolith may have been a very low-key element of the book or may have been a plot element not taken from the book.
I can find a lot of web pages that link Revolution to Ravage, but only in French. This article, among others, attributes an explicit influence of Ravage on J.J. Abrams. I can't find any authoritative reference for that, however, so I don't know whether there was a direct influence or merely plot similitude.
Fade Out seems like the book you are looking for. I read it years ago - as you say, diesel engines worked near the object, with cartridge starters, because they did not depend on a spark. Today diesels do depend on the electrical power in many vehicles. This was a story about a strange object which appeared in a remote part of north America and started sending out a field that nullified electrical signals; gradually the effects became stronger until it started turning itself into a pyramid shape. At this point the troops guarding the object (some on horseback) decided an explosion or radiation was imminent. Sound familiar?