Transmissions need to learn

Dear Doctor: I purchased a 2015 Jeep Cherokee two years ago and it ran beautifully for 18 months. Then the check engine light came on, and the dealership told me it needed a new transmission. After the transmission was replaced it was fine when I drove it home. But the next morning I noticed the Jeep was not shifting correctly. When I brought it back to the dealership I was told the vehicle had to be warmed up to 180 degrees before it would shift properly. Are they right?

— Al

Dear Al: Today’s vehicles have everything electronic, including the transmission. Any time a battery is disconnected, or in your case a transmission is replaced, it can take up to 90 days for the engine and transmission computer to relearn your driving habits. It’s normal for an automatic transmission not to shift into higher gears until the engine coolant temperature is at a specified temperature. Not all transmissions will shift the same, especially ones that are computer updated (re-flashed). The transmission will learn your driving habits and it will change the shifting patterns over a period of 90 days.

Dear Doctor: I recently purchased a 2003 Subaru Forester with 92,000 miles. This vehicle has the automatic transmission with four forward drives. I am using the vehicle as a second car for short trips in my second home in Florida. Should I operate the car in Drive only, or should I sometimes operate it in first, second and third gears?

— Stan

Dear Stan: The good news is you are driving the vehicle in a warm climate, which is much better than the car not being operated in a cold climate while you are in Florida. I would leave the transmission the Drive position. The computer that controls the transmission will always keep the transmission in the correct gear.

Dear Doctor: We own a 2010 Toyota RAV4 with approximately 65,000 miles. Within the last six months, we’ve noticed an awful rumbling noise that intermittently occurs while accelerating. The noise is the worst when the engine is at 1,500 rpm between 35 to 45 mph. Our mechanic wasn’t able to duplicate the noise, but I found the following information on a website blog: “It turns out that it’s essentially a transmission failure. The torque converter is the root of the problem. At 1,500 rpm and 38 to 40 mph, the torque converter in the transfer case was vibrating, causing the heat shield to growl because of the transfer of vibrations.” What are your thoughts?

— Mary Lynn

Dear Mary Lynn: Your Toyota is not the first brand to have a torque converter vibration issue. I recommend you contact the dealer for reprogramming or updates. If there is nothing the dealer can do, then change the transmission fluid and filters and add friction modifier to help eliminate the vibration. The other choice is to remove the transmission and replace the converter.

E-mail questions for publication to Mail questions to: Motor Matters, P.O. Box 3305, Wilmington, DE 19804.

Dear Doctor: I have a 2003 GMC Yukon with the 5.3-liter engine and 245,000 miles on it. While driving there’s an error light indicating “reduced engine power.” When this happens I have no acceleration and must pull over and shut the engine off. After waiting a few minutes, I restart the engine and the error light is off, so I’m able to drive again. My mechanic says code P1516 is coming up, but he says it could be a number of things and can’t figure out what part to change. I welcome your advice. Mike

Dear Mike: A very common problem with many GM vehicles is a fault in the electronic throttle body. Reasons for this range from a bad connector to a bad TPS sensor in the throttle body (which can be replaced for about $100). In most cases you do not need to replace the entire throttle body. Have your technician check both Alldata and Identifix for the needed support information.

Dear Doctor: I own a 2016 Ford Fusion Hybrid. Later this year I plan to retire and spend my winters in Florida and my summers in New York. What can I do to store my hybrid car in New York? It will probably not be used for two to four months at a time. I’m concerned that the hybrid battery will die. Edie

Dear Edie: I would not worry about the hybrid battery at all. My concern would be the regular car battery. I recommend you find someone who will charge the battery periodically.

Junior Damato is an ASE-certified Master Technician.

E-mail questions for publication to Mail questions to: Motor Matters, P.O. Box 3305, Wilmington, DE 19804.