Q: My car is a 2008 Buick LaCrosse with the automatic shift on the steering column. It has begun sticking when in "park" and won't release even though I press the brake pedal hard. I had to push the car forward and back before the shift lever would release. This has happened about five times, the last time while at a GM dealership. They told me that when the car is parked on any type of incline the pressure on the parking "pawl" may cause the problem. They suggest that while the engine is still running in "drive," set the parking brake, then step on the brake pedal, shift into park and then shut off the engine. This seems a rather strange and unorthodox way to solve my problem. And why did it take four-plus years to develop?
A: Actually, the procedure outlined by the dealer — and the owner's manual — is correct. In setting the parking brake first to immobilize the vehicle, there will be no pressure or leverage on the parking pawl, which physically locks the transmission. This eliminates what's known as torque lock — where the weight of the vehicle is "leaning" on the parking pawl, making disengagement difficult.
The other remote possibility is an issue with the automatic transmission shift lock mechanism, which requires depressing the brake pedal with the ignition switch turned on to electronically release the shift mechanism.
I don't have a solid answer for why this problem has developed recently other than wear on the pawl or final drive internal gear that the pawl locks when in park. I'd ask the dealer to use the "range selector lever cable adjustment" procedure to check that the shift cable is correctly adjusted.
Q: I have a 1988 Ford F150 with a 4.9-liter engine and a manual transmission. I have an intermittent problem with the engine cutting out at high rpm. Sometimes it cuts out at a lower rpm or sometimes not at all. The ignition system is the TFI-IV system, which requires no timing adjustment. Any ideas?
A: The most common cause for intermittent ignition problems with this generation Ford is the module itself. I've removed problematic modules for inspection and found visible air bubbles on the surface of the PC board sealed with a thick layer of silicone. You may be able to find a parts store that can test the module to determine if you need a new one.
Q: I have a 2006 Toyota Sienna V6 with 59,200 miles. A notice from the dealer indicated that a valve adjustment should be done on the vehicle. Is this something that needs to be done at this low mileage? The maintenance manual does not have any mention of this requirement.
A: According to my ALLDATA automotive database, Toyota recommends inspecting that valve adjustment at 60,000-mile intervals. Inspecting valve adjustment requires removing the valve covers, rotating the crankshaft into specific positions and using a feeler gauge to measure valve clearance. On the other hand, adjusting the valves is listed as a 5.9-hour job, meaning a cost of $600 or more.
I can't recommend not having the inspection done at 60,000 miles, but if it were my vehicle and I wasn't hearing any clicking, tapping or unusual valve train noises, well, let's just say I'd keep driving the vehicle.
Q: I have a 2006 Toyota Highlander, 6-cylinder, that I purchased new. I have an issue that seems to be getting worse since I've had the car. Sometimes when the car is shifting into third gear and going between 35 to 40 miles per hour, the car jerks. If you accelerate quickly it doesn't do it. The Toyota dealer and a transmission shop have looked at it but could not find the problem.
A: Remember my comments about torque converter slippage described as shudder, chatter or flutter? Could this be the "jerks"? If this only occurs shifting into third, service literature points toward the "direct and overdrive clutch."