Computers Make Me Stupid
Oct 08, 2009
I did it again. I allowed computer technology to overshadow common sense.
A light on a combine didn't work. Common sense says the first step is to replace the bulb, or at least test for voltage at the socket. When I stepped out of my truck the customer assured me that he had already "replaced the bulb with one I robbed from another light on the combine," so I hopped in the combine cab and used the on-board diagnostic system to see what was the problem. After several hours of testing voltages and resistances at a dozen or more electrical connectors in a half dozen wiring harnesses, and experimenting with replacing a $900 computer board that did nothing to make the faulty light work properly, I calmed down and used common sense. I replaced the bulb, and the light worked. Duh. The customer is still scratching his head trying to figure out why switching lights didn't identify that the bulb was bad. But the bottom line is that the first step in diagnosing any problem is to do the easy, obvious stuff before the sexy, high-tech, complicated stuff.
For those of you who like technical stuff, here's a warning based on my little escapade: Remember when lights were turned off and on by a simple switch that did or didn't allow current to flow through the lights' positive wire? Not any more. That one light--which happened to be on the unloading auger--is powered and controlled through a computer board that takes the on/off signal from the main light switch, compares it to sensors that track whether the unloading auger is swung in or out, adds inputs from the overall lighting system controller, then decides whether to turn the light on or off by opening or closing the NEGATIVE side of the light's circuit.
No wonder farm equipment is so expensive.