Q I have a 2004 Ford Expedition with a 5.4-liter engine. Over the past few months, my remote key fob will intermittently unlock only the driver's door and not all the doors. If I open the door and push the unlock button, they will all unlock. A new battery in the fob did not help. Normally, when the engine is shut off, and the key removed, the radio and other accessories will turn off when the door is opened. Now, when I open the driver's door from the inside, the accessories will not turn off. It has gotten progressively worse over the last few months. The passenger door always turns things off. Could the remote locking and the accessories issues be related? Is there a switch or connector inside the driver side door that could be causing the issue?

A I'm glad you included the fact that the passenger door "always turns things off." That's a key piece of information. The VSM (vehicle security module) located in the passenger footwell individually controls the driver and passenger door lock/unlock relay. This module or its connections may be at fault.

The other possible source of trouble is the driver door switch and/or the driver door ajar switch, both located inside the driver's door. I'd suggest an initial scan test looking for possible B-series (body control module) fault codes.

Q I have a 1996 Cadillac Deville with 81,200 miles on it. I have a constant problem with the theft deterrent system disabling the starting of the car. Failure to start after the "three minute program" is common, and it can be several hours or even several days before the car will start. I have been left stalled in a parking lot and I had to have the vehicle towed once -- only to have it start almost immediately after being towed to my driveway. I have contacted several dealers and their suggestions range from replacing the key cylinder, replacing the key (I seriously doubt the chip is the problem) and even installing a new vehicle computer.

My question: Is there a code to reset the computer so that the vehicle will start after being disabled by the theft deterrent system? Is there a code to delete the theft deterrent system from the vehicle? Is there some other way to correct this system?

A There's no reset code and no way to delete the anti-theft system from the vehicle. But there is a very strong possibility of a DTC fault code stored in the vehicle's powertrain control module (PCM) or body control module (BCM). If you haven't had the dealer perform a scan of these modules, that should be your first step. A 2700-series instrument panel DTC fault code could point to the specific problem -- which may well be a faulty chip on the ignition key. Do you have a spare?

Q I have an '02 Toyota Camry V-6 with 118,000 miles. After driving about 100 miles, when I come to a stoplight the RPMs drop to 100-150 and the engine dies. It will restart but stall again. If I rev the motor, it will keep running. If I leave it sit for 5 to 10 minutes, it will return to normal. It does this maybe two to three times a month. The Check Engine light does not come on.

A Sounds like a loss of fuel pressure. Underhood heat may be causing the fuel to percolate in the fuel rail mounted on the engine. The boiling fuel creates air bubbles, which disrupt the spray of fuel from the injectors -- thus the poor idle/stalling. Restarting and keeping the engine RPM moderately high for a few moments often clears the overheated fuel from the rail. Ditto for allowing the vehicle to sit and cool for several minutes; it lowers the temperature of the fuel, stops the percolation and clears the vapor lock.

Additional factors could include a restricted exhaust or partially clogged catalytic converter, excess engine or underhood temperatures due to cooling system problems, and perhaps your choice of fuels.