Dear Tom and Ray: We recently purchased a 2003 Honda Civic with 80,000 miles. The previous owner was very fastidious about maintenance, and had replaced several major items within the past six months, including the timing belt, for which he provided us receipts. My husband was driving the car recently and accelerated to pass another vehicle, when the Civic suddenly lost power and some of the dashboard lights came on. Fortunately, he was close by, and was able to limp home at a slow speed. We had the car towed to the repair shop that we have used previously, and they diagnosed the problem as a burned-out alternator and PCM.

The mechanic told us that the problem was caused because when the timing belt was replaced, the alternator was left loose and not grounded. He said that when there was a power surge during acceleration, both the alternator and the PCM burned out. The repair bill was $1,200. We contacted the shop where the timing-belt repair was done, and the owner denies that his work would have caused this damage. He said our repair shop sold us unnecessary parts, and said the alternator is not touched when a timing belt is installed. He also pointed to the five-month span between the time the work was done by his shop and the alternator problem, and suggested that any problems with the repair would have shown up sooner. We don't know what to believe. What do you think? -- Kathi

TOM: Well, first of all, you have our condolences, Kathi. The PCM is the powertrain control module, also known as "the computer." That's why this repair was so expensive.

RAY: Is the story possible? Can an ungrounded alternator cause this damage? I'm sure it can. I've never wanted to find out, so I've always made sure my customers' alternators are grounded when they leave the shop. But inadequate grounding can potentially cause a host of electrical problems.

TOM: But can you attribute it directly to the guy who changed the timing belt five months ago? That's almost impossible, at this point.

RAY: He had to loosen the alternator to remove the car's other belts in order to get at the timing belt. So it's possible he neglected to tighten the pinch bolt that grounds the alternator to the bracket through its housing.

TOM: But then why did it take five months to fail? I suppose it could have loosened up more and more over time until it was not grounded at all, but on a 10-year-old car, one of those could just as easily have failed on its own for another reason.

RAY: Or it's possible that the guys at your shop were the ones who were mistaken, or dishonest.

TOM: I sympathize with you guys. You just got what is supposed to be a reliable car, and you immediately had an expensive and unexpected repair. But that sometimes happens with cars, even when it's nobody's fault.

RAY: So my advice would be to forget about it and move on with your lives. I don't think you'll ever know for certain whether this was somebody's fault unless you engage CSI: Midas Muffler. So assume there was no evil deed done here -- the car just broke down -- and don't lose any more sleep over it.