Without spending a great deal of time, you should be able to turn things around for your son. Begin by playing detective. You can find out a lot about his reading skills by having him read to you from one of his textbooks. If his skills seem weak, talk to his teacher about how they can be improved. Since he is doing well in school, we would guess that his reading skills are at least on grade level.
If your son is watching considerable television, it is probably cutting into time that could be used for reading. We suggest that families set aside 20 minutes each day for free reading. Everyone sits down and reads during this time, which is protected from phone calls, visitors, and other distractions. If your son is reluctant to read, you might begin by having him use this time to put together a model that requires the reading of fairly complicated directions.
Your child needs to understand that reading is essential. He should see you reading a wide variety of materials, from magazine advertisements to office work.
The most important way to hook your son on reading more is to show him reading is fun. Have a great variety of reading materials lying around the house, even in the bathroom. Make it easy for him to pick up something to read -- from a comic book to a children's version of such adult magazines as Sports Illustrated and National Geographic.
Don't just expect your child to read. Read to him every day. Try humorous materials, silly stories, and popular book series. This will truly show him that reading can be fun.