<human>: My brother is almost 17. He's a junior in high school. He has a vehicle and has not made it through a full week of school this whole year because he just gets in his truck and drives away. My mom won't take his truck away because they live 45 minutes away from the school and she can't/won't drive him. 

He consistently fails at least one class each 6 weeks, with comments from his teachers like "lack of interest/effort." I was very self-motivated, and my mom doesn't know how to handle this situation. She did absolutely nothing to get him on track in his early years of high school, but yet she's confused about why he's messing up so badly. Her previous attempts (basically just screaming and calling him a loser who's not going to graduate) failed miserably.

I overheard him the other day talking to his friends about smoking weed. I *think* he's skipping class to go smoke with his friends. I don't think smoking is something horrible, but the issue is that he's skipping/failing and generally being an irresponsible teenager. I really don't think it's a good idea to tell my mom about his decision to smoke, because she won't handle it well. 

I'm very concerned about him. I don't think it's too late to turn things around, but he's difficult to approach. He has that typical teenage boy "I'm always right and I know everything" mentality. Any advice would be greatly appreciated. Thank you.

Can you condense the text into three sentences or less?
<bot>: teenage brother is skipping school, failing, and smoking marijuana. I don't want to tell my mom, she's an inflammatory person who will just go into attack mode and won't actually do anything productive.