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Q: Before taking a 2,600-mile road trip, the LDW [lane departure warning] signal saying system failure came on in my 2016 Honda Odyssey. I took it to the dealer. The first gentleman said he saw a lot of pine sap on my car and thought that perhaps it was confusing the camera. He had the car washed and said it was good to go.

The next morning the lights appeared again. I returned to the dealer. They ran a diagnostic test, and it said that I needed a new control box, but they didn't have one in stock. So we went on our trip without it, and the lights did not appear again.

About a week after returning home, it started all over again. I cleaned the camera on the rearview mirror and washed the window inside and out, and the warning lights have not reappeared. What is your opinion? Do I really need to replace this box, or was the first gentleman correct that it was just a dirty window?
A: I think that the first guy probably was right. My philosophy is to do the easy stuff first. That would be to clean everything that might be impacting the camera's view. Control boxes seldom fail; that's why they don't keep them in stock. Check your owner's manual for instructions to turn off the LDW, and then turn it back on. This might reset the warning light.

Misleading numbers

Q: I have a 2019 Toyota Highlander with 22,000 miles. A key fob battery-replacement warning has appeared on the display twice since I purchased the car. Each time I have checked both the in-use battery and a fresh one with DC voltage meters. Same results: new 3.3 volts, used 2.9 volts. Your opinion, please.
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 surely will let you know.

Too much juice

Q: I had to replace the five-plus-year-old battery in a 2009 Chevrolet Impala because it would not hold a charge. 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? I have always thought that the voltage output of an alternator should be 13.5 to 14.6 volts.
A: You are right regarding the normal alternator output. 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.

Bob Weber is a writer, mechanic and ASE-certified Master Automobile Technician. His writing has appeared in automotive trade publications, Consumer Guide and Consumers Digest. Send automotive questions along with name and town to