Q The power lock on the left rear door of my '94 Buick Regal no longer locks. I took the car to the shop where they said to just save my money and lock it manually by pushing the button down. But now the power window in that door doesn't work -- it won't go up or down. The other three windows work fine. What's causing this?

A The wiring harness for both the power door lock and power window are routed through a rubber duct between the door post and door, and are flexed every time the door is opened/closed. Since neither the power door lock nor window function, it's entirely possible there's a frayed or broken wire inside this harness.

Also, since the door pivots on lubricated hinges, the door frame is electrically grounded by a wire traveling through the same harness. The quick test for a poor ground is to use jumper cables to create an additional ground connection between the door frame and car body, then test the power door locks and windows. The next step would be to check for voltage in the mutli-terminal connector C351 that carries voltage into the door to operate the lock and window.

QI have a '97 Jeep Grand Cherokee. All of a sudden all my power windows and power door locks quit working. All the fuses and relays have been checked and even replaced as a precaution. When I replaced the vehicle's battery the windows and door locks worked for a few minutes then quit again. Also, the keyless entry remote will not unlock the vehicle. The driver's side window still works and the driver's side power door lock works occasionally. The dealer just wants to sell me a new vehicle.

AAsk the dealer to connect Chrysler's diagnostic scan tool, called the DRB, and check for fault codes from the BCM -- body control module. Specifically, look for fault codes from the electronic door modules in each front door. The problem may be a simple as a poor connection or ground in one of the two door modules.

QI have a 2001 Chevy Blazer with 195,000 miles on it. For the last year or so the engine will shut down intermittently while driving at any speed from 30 to 65 mph. It always starts right back up after it dies but there is a smell like burnt matches. I've taken it to several mechanics but it's always running at the time so they say they "can't fix it if it ain't broke."

AWith that many miles on the vehicle and hundreds if not thousands of 'on-off' cycles with the ignition key, I'm suspicious of the ignition switch in the steering column. If there are no fault codes from a computer scan and your nose leads you to the steering column as the source of that burnt matches smell, the ignition switch may be worn to the point where one or more electrical contact inside the switch is "arcing" or burned to the point of intermittent connection.

QI have a 2010 Dodge Grand Caravan. At speeds over 50 mph and on windy days there's a noise coming through the ventilating system that sounds like a kid with waxed paper over a comb, playing it like a harmonica. After three trips to the dealer the noise is still there.

AI've experienced a similar condition with one of my vehicles recently and it turned out to be the plastic cowl molding at the base of the windshield. I confirmed the source by duct taping the edges of the cowl molding, sealing them to the glass -- no more noise.

My Alldata database found Chrysler service bulletin No. 23-11-010 describing a buzz or rattle from the right front door glass that's been traced to the door lock rod.