Diagnostics took a while to become a high art, and you could easily argue that it’s no longer a human activity at all. Just look at how much can be accomplished by digital gizmology that can tell you who made a lousy shift in truck #655 two Wednesdays ago just east of Des Moines at 3:19 in the afternoon. If you ask.

Things were different back in horse-and-buggy days, when hauling freight was a simpler mechanical enterprise than it is now. You could see every single part of your trailer, and when something broke, it didn’t take hours of shop time to figure it out. And, best of all, it was never a wiring issue.

Your one-horse “engine” wasn’t really a whole lot different. When the nag pulled up lame, you probably just needed a new shoe. Diagnostics was easy as pie.

Then, for a very long time, it was the era of The Stare. Once engines began to be made mostly of iron instead of equine flesh and bone, and we multiplied their paltry power by means of steel gears, the art of mechanical diagnosis was born. From that point until the advent of the electronic engine, mechanics were often to be found standing 10 feet from the failed truck, staring at the darned thing. Sometimes they huddled in groups, as if ingenuity could be expanded by piling one befuddlement on top of another.

Engine diagnostics began with desperately simple questions such as, is it getting fuel? Or in the case of gas motors, is it getting spark? Now we ask those same questions in very different ways.

Diagnostics really did become an art. For some folks, anyway – the intuitive ones. And the guys who took it to its highest level were elevated to star status.

Truck Whisperers, they were called. Legends.

As things got progressively more complicated, we devised another means of multiplying ingenuity. We began calling mechanics “technicians.” It was a brilliant stroke, the logic being that the moniker made the mechanic more confident and thus better matched him to any problem’s complexity.

When electronically controlled engines rolled onto the scene, often sputtering, some operations went so far as to equip their shops with computers. Never mind that they were usually tired old machines that the front office had butchered for a few years before sending them out back to the poor old maintenance lads.

The technicians out there could finally live up to their names. Except that many of them spent as much time diagnosing computer glitches as they did fooling with engine faults.

We’ve made enormous progress since then.

Today, nothing’s as obvious as it could be in those buggy-wheel and earliest mechanical years, but the diagnostic art has changed radically and become easier than ever. The very concept of complexity gets redefined every day – but so do our tools.

Ironically, our trucks are almost as transparent now as our horse-drawn wagons were. They’re wildly complex machines, but the vast array of data streaming out of them makes the diagnostics task no harder than seeing the bad spoke on a wooden wheel.

In theory. On a good day.