Q: Our 2007 Buick Rendezvous at times will not shift from Park. It seems frozen there. If we turn on the ignition and put it in neutral, then it will let us shift. Help!

A: I’m confused! You seem to be describing correct operation of the shift interlock system. Here’s how the system is designed to operate: With the ignition switch in the on position and the shift lever in Park, voltage is supplied through the transmission control switch to the transmission lock solenoid, energizing the solenoid and physically locking the shift lever in Park. When the brake pedal is then applied, the transmission control switch is de-energized, releasing the lock solenoid and allowing the shift lever to be moved out of the Park position.

You didn’t say whether you’re applying the brake pedal during the “no shift” episodes, but with the key in the on/run position, you should not be able to move the shifter out of Park unless your foot is on the brake pedal.

If you cannot move the shift lever with the ignition in the on/run position and your foot on the brake, the culprit is likely the transmission control switch or shift lock solenoid, or their connections.

 

Q: My wife and I own a 2013 Chrysler 200 that we both like. It’s her car and I drive it once in a while. I have one complaint. While driving at highway speeds and going over large horizontal cracks or seams in the pavement, it feels that the car slides to the side a little. It’s more prominent when traversing a light curve or worse yet a sharper curve, as then the rear end almost jumps sideways.

Can tire pressure cause this? She tends to keep the tire pressures up higher in the winter months so the tire pressure sensors won’t yell at her for being too low in the cold weather. Now that it’s summer, I just lowered the pressure in each tire to 34 psi. They were at almost 40 psi. I haven’t driven the car since so I’m not sure if the problem is solved or not. What are your thoughts?

 

A: Tire pressure plays more than one role in vehicle performance. The tire is part of the suspension and acts like a spring in absorbing some percentage of the bumps generated by road irregularities. The higher the tire pressure, the stiffer the spring rate. Thus, an overinflated tire may well contribute to the skipping or sliding characteristic you’ve described.

Best I can tell, the recommended tire pressures for this vehicle are 32 psi in all four tires. Adjust the tires to this pressure and drive the car for several days. Is the ride quality better? Since this vehicle is front-drive, you could perhaps try lowering the rear tire pressures a few pounds to “soften” the rear spring rate.

 

Q: I am considering buying a Chevy Malibu with the Turbo 4 engine. As a dedicated Toyota/Mazda owner I am somewhat nervous about buying an American car, for reliability reasons. Is the Turbo 4 in the Malibu the same as that in the Buick Verano and Cadillac ATS? If so, that would give me some reassurance if there are other makes using the engine without issues.

 

A: Yes, the same family of GM Ecotec four-cylinder, double-overhead-cam turbocharged engines are available in these three vehicles, along with a number of other GM vehicles worldwide. Much of the original design and engineering for this engine was done by Opel, GM, Saab and Lotus Engineering.

In today’s automotive world, there really are no purely “American” cars. Virtually every make and model is a “world” car with design, engineering, parts and production originating from many countries.

This family of GM engines has been produced since 2000 — 15 years. No worries, it’s a well developed, dependable powerplant.