For years, I have read trade magazines written by and for professional mechanics. I especially enjoy the articles describing difficult-to-diagnose repairs. Symptoms such as an engine failing to start or stalling leads to methodical, meticulous testing of systems and individual parts. The clues often point to an electrical or computer problem. The problem might be intermittent or connecting an OBD scan tool reveals a slew of confusing diagnostic trouble codes.
The technician will often bring out an oscilloscope and start checking the signals from and between computer modules. As I read the painstaking details, I start to worry if what my granddad told me in the 1970s, “These new cars are too complicated to work on.” finally has proved true 40+ years later.
After reading lots of articles, I have stopped worrying. The sophisticated electrical testing may help identify the troublesome system, but the specific broken part is often found using classic troubleshooting techniques that have been around since cars were first invented. Techniques such as jiggling connectors, swapping in new parts, cleaning off corroded ground connections and looking for physical damage.
Yes, that BCM (Body Control Module) under that late model GMC truck’s seat is high tech, but the layer of corrosion covering it looks a lot like the corrosion that can build up on the battery terminals of a 1960s GMC truck. The IDM (Diesel Fuel Injector Driver Module) behind the fender liner on that newer Ford truck is sophisticated electronics, but fill it with dirty water and there will be problems similar to those experienced when water gets inside a 1968 Ford Bronco’s distributor cap. The trade journal articles have also revealed a rat’s teeth can gnaw through important wires on a new car just as easily as wires on an antique car.
A professional mechanic may not get much background information on the vehicle in his/her service bay. A DIYer has the advantage of knowing his/her vehicle’s history of repairs/maintenance, modifications (new radio recently installed…) and potential sources of damage (major coffee spill under the front seat…). That information can point out where to start the hunt and turn a difficult-to-diagnose repair into a straightforward repair.