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Q: I just had my car washed at a popular local facility. I watched almost every customer hit the "free" undercarriage rinse button. Could that rinse water be recycled from the wash process? This time of year with so much road salt being washed away, I wondered if we were getting a "saltwater rinse." I imagine that would simply hasten early rust and corrosion. What do you think?

B.L., Indian Head Park, Ill.

A: We turned to Eric Wulf, the CEO of the International Carwash Association, who stated: None of the water that is re-used and recycled in the wash process is unfiltered. Meaning, the water used for undercarriage washing is going to be filtered of much of the salinity you fear — certainly it will have much less salinity than the "raw salt" sticking to the underside of the vehicle.

Q: G.R., of Pompano Beach, Fla., wrote about his key fob not working all the time and the door locks clicking on and off. My son's Chevy Uplander and my 2005 Pontiac Grand Prix had the same problem. We traced the problem to the rubber portion of the key fob; the coating applied under the lock-unlock buttons had worn off due to many lock-unlock uses. We used foil tape and a paper punch to cut small foil disks that we placed under each button and that fixed the problem. It is temporary, because the foil disks come loose and have to be replaced after a while. The trunk button never had a problem because it receives less use.

J.N., Somonauk, Ill.

A: Other readers have reported that the electrical compound on the key fob pads wears off. We experienced the same problem some years ago with a telephone keypad as it became more difficult to press certain numbers, so we opened it up. Using some automotive rear window defroster repair compound, we painted the contacts and then the phone worked for a couple of years. For those who are less do-it-yourself-inclined, buying a new key fob is the answer.

Q: I work for a fleet maintenance company solving unusual driver complaints. Regarding the 2015 GMC Terrain issue (a reader's SUV had a dead battery possibly linked to a computer problem), I've come upon a similar complaint twice. The cause was related to the OnStar. The OnStar was never activated or subscribed to by the driver. The corrective was to contact OnStar (separate from GM), fill out the release on the terms and conditions and then, with the vehicle running and stopped in a safe place, contact OnStar to allow them to send a software patch to prevent OnStar from keeping the body control module awake intermittently when the vehicle was turned off. Both the vehicles I assisted on had been to multiple dealerships. The ghost draw was resolved in both cases.

M.M., Chicago

A: Modern vehicles often receive pushed software patches while the vehicle is parked — usually overnight. Anything that awakens the BCM, but does not allow it to go back to sleep, could cause an intermittently drained battery. Thanks for the input.

Bob Weber is a writer, mechanic and Master Automobile Technician.