Quick clean or expensive fix?

Q: I have a dilemma. A month ago, before taking a 2,600-mile road trip, some of the yellow lights came on on my dashboard. One was the LDW signal that said system failure. I took my 2016 Honda Odyssey to the dealer. The first gentleman said he saw a lot of pine sap on my car, perhaps it was confusing the camera. He had the car washed and it was good to go. The next morning the yellow lights appeared again. I returned to the dealer. They put it on their machine and it read out that I needed a new control box but it was not in stock. I had to pay $745 for them to order it. We went on our trip, the yellow lights did not appear again. About a week after returning home it started all over again. I did some research on my own. I cleaned the camera on the rear-view mirror, cleaned the window inside and out, and the yellow warning lights have not reappeared. What is your opinion? Do I really need to replace this box or was the first gentleman correct when he said it was a dirty window?

D.S., Arlington Hts., Illinois

A: I think that the first guy was probably right. My philosophy is to do the easy stuff first. That would be to clean everything that may be impacting the camara’s view. Control boxes seldom fail; they don’t keep them in stock. Check your owner’s manual for instructions to turn off the lane departure warning (LDW) and then turn it back on. This may reset the warning light.

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Q: I have a 2019 Toyota Highlander with 22,000 miles. A key fob battery-replacement warning on the display has twice led me to undertake this task since purchasing the car. Each time I have checked both the in-use battery and a fresh one with DC voltage meters (I have 2). Same results: New 3.3 volts, Used 2.9 volts. Your opinion please.

C.M., Deerfield, Illinois

A: Open circuit voltage isn’t always a true sign of a battery’s energy. Even a reading of 3.0 volts can mean the battery has only about 10% life remaining, At 2.9 volts, your car will surely let you know. But I must ask where you are buying your batteries. If it’s online and you are selecting bargain batteries, you may be getting crappy batteries. Buy a name brand from a reputable store. I bet it will last 2-3 years. Did you know that you can start your engine even if your fob battery is dead?

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Q: I had to replace the five-plus-year-old battery in a 2009 Chevrolet Impala LS because it would not hold a charge after the engine had been turned off. The car runs fine with the new battery, but the alternator is putting out 14.7 to 14.9 volts. Is this an acceptable voltage or will it diminish the life of the new battery? Should I replace the alternator, which costs about twice as much as a new battery? I have always thought that the voltage output of a good alternator should be 13.5 to 14.6 volts.

P.S., Frankfort, Illinois

A: You are right regarding the normal alternator output. If your vehicle has an amperage gauge, it will normally hover around 14.2 volts. If an alternator is producing more than 14.5 volts, it is overcharging and can damage the battery. Many parts retailers can run an alternator test, usually for free. Before buying a new alternator, have yours analyzed.