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Car Doctor: Mercury headlights go out while driving

Posted by John Paul  August 2, 2011 11:38 AM

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Q. I own a 2004 Mercury Grand Marquis with about 115,000 miles. For about the last six months the headlights have been going out when I'm driving. Lately it has increased in frequency. I have checked all the fuses and the headlight switch seems to be functioning. When the headlights go out, the other lights remain on. Would this indicate a short or some other problem?

A. The most common problem is the lighting control module. Just to warn you, the part is $500 plus installation.

Q. I have a 2004 Ford Explorer and for the last year and a half it has occasionally decided not to start. This happens after it has been driven, parked and a short time later restarted. The engine doesn’t turn over or even click. This problem now occurs almost once a month and is getting very frustrating. The more I drive the longer the period necessary for it to restart. Hopefully you will have some ideas, since otherwise the car runs very well. I’m a bit of a DIY’er so is there something I can try?

A. The problem sounds like in intermittent open circuit to the starter relay or a faulty starter relay. The starter relay is inexpensive and easy to change. Although I don’t usually believe in guessing, it may be worth a try.

Q. My daughter drives a Jeep Liberty that has a feature I like: Optional four-wheel-drive mode. The vehicle normally uses two-wheel-drive mode. If the snow flies, the driver has the option of shifting into four-wheel-drive mode. Do you know of any other cars that offer that feature?

A. Many vehicles use this manual four-wheel-drive feature as a method to save fuel, although as a four-wheel-drive system it may not always be the best choice for every driver. Most drivers either shift into four-wheel-drive too late or too early. Automatic all-wheel-drive systems will quickly shift from front- or rear-wheel-drive to all-wheel-drive as soon as the wheels begin to slip.

Q. I have a 2002 Ford Explorer; the truck runs great, although intermittently the overdrive light on the dash has been showing up. When the light is on, the truck doesn't run any differently and the light will reset itself when the truck is restarted. I have been checking on the internet and it appears there is really no set solution. I brought the truck into a local mechanic and he stated he is 99 percent sure it is a sticking valve. Do you know if this issue was subject to any recalls? Do I chance the repair with the hopes that the $500 charge to replace valve doesn't lead to a $3,000 transmission repair?

A. The two most common problems are a faulty torque converter or a worn overdrive servo. Have a technician scan the truck’s computer for fault codes — this should help them make a determination of the cause of the problem. If the overall vehicle condition is good, spending $500 or even $3,000 may be worthwhile.

John Paul is the public affairs manager for AAA Southern New England. He can be reached at or on Twitter @johnfpaul.

This blog is not written or edited by or the Boston Globe.
The author is solely responsible for the content.

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Clifford Atiyeh is an automotive writer and car enthusiast . He has spent his entire life driving cars he doesn't own.
In the garage: 1995 21-speed Iron Horse, 2002 Jeep Wrangler X (by association)
Bill Griffith is a veteran Boston Globe reporter, having reviewed cars for more than 10 years and serving as assistant sports editor for 25 years. He was also the paper's sports media columnist.
In the garage: 2006 Subaru Baja
AAA's Car Doctor, John Paul John Paul is public affairs manager for AAA Southern New England, a certified mechanic, and a Globe columnist. He hosts a weekly radio show on WROL.
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Craig Fitzgerald has been writing about cars, motorcycles, and the automotive industry since 1999. He is the former editor of Hemmings Sports & Exotic Car.
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Keith Griffin is president of the New England Motor Press Association and edits the used car section on He also writes for the Hartford Business Journal and various weekly newspapers in Connecticut.
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