Nevertheless, I work on all my own vehicles. One current one is a 1972 Chevy fullsize, and yes, there is a lot of room and not a whole lot of complexity in there (though I did add fancy-schmancy power steering). The latest is a 2000 Saturn SL2, with a DOHC (moderately complex).
There isn't that much to electronics. Basically, you need to understand resistive networks, batteries (that's the oxygen sensors), basic induction, and the concept of pulse width modulation. There are many, many books on these subjects in automotive applications, or a couple of classes at the local community college will take care of it.
The idea that electronic engine management is "more complex" than old stuff is simply not true. It does all the same stuff, slightly differently. Frankly, the most complex engine management I've seen was the last generation of carbureted engines. For instance, the Ford 2.8L Cologne V6's. It has mechanical, vacuum, thermal (bimetal), and electrical controls, all combined. The very next year, they morphed into the 2.9L with multiport fuel injection, and it was a lot simpler and more reliable.
What has grown in complexity is the scope of self-tests, and continuous monitoring. That's a simplification. In an OBD-II vehicle, I get several different indications of oxygen sensor problems, some of which can only be due to a fouled or consumed sensor (such as slow transition times). In OBD-I, I'd just get a lean code, which could be due to a lot of things (not the least of which is poor electrical grounding). In a carbureted vehicle, it would just run poorly with an incorrect mixture or a large change in altitude, and they aren't adjustible without tearing down the carburetor.
