Q: I have a 2009 Chevrolet Silverado Crew Cab, and the courtesy lights don't come on when I open the driver's door. They do come on when I open any other door. Should I be looking for a blown fuse? Everything else in the driver's door works OK.

A: Unlike other makes that use a plunger-type doorjamb switch mounted at the body to activate the interior lights when opening a door, most late-model GM products incorporate the switch into the latch assembly inside the door. That switch in the latch assembly is most likely the problem. Accurate testing would require a scan tool where you can view the inputs to the body control module. If the data shows all the switches working when opening all doors but the driver's, that will point to the latch assembly. Further testing could confirm the wiring from the switch and the body control module working correctly, which would confirm the switch in the latch being the cause. It should cost about $300 parts and labor at the dealership.

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If you have a technical question regarding your pickup, SUV, or van, feel free to contact Alex, a master technician with the National Institute for Automotive Service Excellence. Send a letter to him in care of Truck Trend Garage, 831 S. Douglas Street, El Segundo, CA 90245, or e-mail us at trucktrend@sorc.com. Please include the VIN with your question. Due to the volume of questions received every month, we cannot guarantee that everyone's question will be personally answered or will appear in the magazine.

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